Composition of vinyl ether group-containing (meth) acrylic acid ester and production method thereof

ABSTRACT

It is an object of the present invention to provide a vinyl ether group-containing (meth)acrylic ester, which has both radical polymerizability and cation polymerizability, improved in storage stability and stability in handling without impairing its polymerizability or, in other words, provide a stabilized vinyl ether group-containing (meth)acrylic ester. Another object is to provide a method of producing a stabilized vinyl ether group-containing (meth)acrylic ester composition. A further object is to provide a method of stably handing, a method of economically and stably producing and a method of purifying a vinyl ether group-containing (meth)acrylic ester.  
     A vinyl ether group-containing (meth)acrylic ester composition which comprises a radical polymerization inhibitor and a vinyl ether group-containing (meth)acrylic ester represented by the following general formula (1): 
     CH2=CR1-COO—R2-O—CH═CH—R3  (1) 
     in the formula, R1 represents a hydrogen atom or a methyl group, R2 represents an organic residue and R3 represents a hydrogen atom or an organic residue.

TECHNICAL FIELD

[0001] The present invention relates to a vinyl ether group-containing(meth)acrylic ester composition and a method of producing the same aswell as to a method of handling, a method of producing and a method ofpurifying a vinyl ether group-containing (meth)acrylic ester.

[0002] More particularly, it relates to a composition comprising a vinylether group-containing (meth)acrylic ester having different kinds ofpolymerizable groups within the molecule and capable of being easilyhomopolymerized or copolymerized with some other polymerizable compoundsby means of heat, ultraviolet rays, radiant rays, electron beams,radical polymerization initiators or acids, etc., and a method ofproducing the same as well as to a method of handling, a method ofproducing and a method of purifying said vinyl ether group-containing(meth)acrylic ester.

BACKGROUND ART

[0003] Vinyl ether group-containing (meth)acrylic esters have differentkinds of polymerizable groups, namely radical- and anion-polymerizable(meth)acryloyl groups and cation-polymerizable vinyl ether groups,within molecules and, therefore, they are useful compounds which can beused in a wide range of industrial use as raw materials in medicinalchemicals and agrochemicals, as synthetic intermediates and further aspolymerizable materials.

[0004] A number of studies have been made on the radicalpolymerizability and cation polymerizability of vinyl ethergroup-containing (meth)acrylic esters. However, because of their easyradical polymerizability and cation polymerizability, vinyl ethergroup-containing (meth)acrylic esters are poor in stability, which leadsto impurity formation, peroxide formation and polymerization duringstorage or handling thereof, hence they can hardly be said to be putinto fully practical use.

[0005] For methods of producing vinyl ether group-containing(meth)acrylic esters, there are known the method comprising subjecting(meth)acrylic acids and hydroxyl group-containing vinyl ethers toesterification (method A), the method comprising subjecting(meth)acrylic halides and hydroxyl group-containing vinyl ethers toesterification (method B), the method comprising subjecting(meth)acrylic anhydrides and hydroxyl group-containing vinyl ethers toesterification (method C), and the method comprising subjecting(meth)acrylic esters and hydroxyl group-containing vinyl ethers totransesterification (method D), and the like. The above esters can alsobe produced by the method comprising subjecting (meth)acrylic acids andhalogen-containing vinyl ethers to esterification (method E) and by themethod comprising subjecting (meth)acrylic acid alkali (or alkalineearth) metal salts and halogen-containing vinyl ethers to esterification(method F).

[0006] Of these production methods, those methods usinghalogen-containing vinyl ethers as starting materials cause theformation of an equimolar amount of by product salts. Therefore, thoseproduction methods using hydroxyl group-containing vinyl ethers asstarting materials are suitable from the industrial viewpoint. Since,however, hydroxyl group-containing vinyl ethers are generally producedby the addition reaction of diol to acetylene (the so-called Reppereaction) or by the gaseous phase dehydration reaction ofdiol-monoalkylene oxide adduct, a number of impurities are formed asbyproducts. Since these impurities have properties such that are closein boiling point to hydroxyl group-containing vinyl ethers, formazeotropic compositions therewith and are close in polarity thereto, forinstance, a complicated purification is required for the completeisolation to obtain pure hydroxyl group-containing vinyl ethers and costof production of pure hydroxyl group-containing vinyl ethers isincreased thereby. Consequently, the vinyl ether group-containing(meth)acrylic esters produced by using such hydroxyl group-containingvinyl ethers as starting materials become expensive. Thus, the advent ofmethods of producing vinyl ether group-containing (meth)acrylic estersat low cost using hydroxyl group-containing vinyl ethers as startingmaterials is awaited.

[0007] Another problem is that since vinyl ether group-containing(meth)acrylic esters, when produced by any of the methods (A) to (F),decompose during the process of production thereof, leading to impurityformation, peroxide formation and polymerization, it is impossible tostably produce them.

[0008] The method of producing vinyl ether group-containing(meth)acrylic esters which comprises subjecting (meth)acrylic ester anda hydroxyl group-containing vinyl ethers to transesterification isadvantageous from the industrial viewpoint since it does not use anyexpensive or hazardous raw materials. However, it has the problem thatthe yields of vinyl ether group-containing (meth)acrylic esters isdecreased by polymerization occurring in the reaction system. Further,there is another problem that peroxide formation due to the excess ofmolecular oxygen and impurity formation due to decomposition. There is afurther problem that since the starting material hydroxylgroup-containing vinyl ether, and the product vinyl ethergroup-containing (meth)acrylic ester each has a vinyl ether group, sidereactions such as polymerization of the vinyl ether groups of theproducts and starting materials as caused by (meth)acrylic acid formedin trace amounts due to water occurring in the system and isomerizationof the starting material hydroxyl group-containing vinyl ether to thecorresponding 2-substituted-1,3-dioxo compound occur.

[0009] For the method of purifying the vinyl ether group-containing(meth)acrylic esters produced by such methods as mentioned above, thereare known the techniques of extraction, washing with water, evaporation,distillation and column chromatography, etc. However, because of theeasy radical polymerizability and cation polymerizability of vinyl ethergroup-containing (meth)acrylic esters, polymerization occurs in theprocess of purification and, further, impurity formation may easilyoccur as a result of decomposition. Accordingly, vinyl ethergroup-containing (meth)acrylic esters can hardly be said to beproducible stably from the industrial viewpoint. The quality and storagestability problems of the product obtained still remain unsolved. Thus,there is room for investigation with a view to prevent the formation ofimpurities as a result of polymerization and decomposition of vinylether group-containing (meth)acrylic esters in the stages of storage,handling, production and purification thereof and thus render such vinylether group-containing (meth)acrylic esters fully practical forindustrial use.

[0010] The present invention has been made in view of theabove-mentioned state of the art. Accordingly, it is an object of thepresent invention to provide vinyl ether group-containing (meth)acrylicesters, which has both radical polymerizability and cationpolymerizability, improved in storage stability and stability inhandling without impairing its polymerizability or, in other words,provide stabilized vinyl ether group-containing (meth)acrylic esters.Another object is to provide methods of producing stabilized vinyl ethergroup-containing (meth)acrylic ester compositions. A further object isto provide methods of stably handing, methods of economically and stablyproducing and methods of purifying such vinyl ether group-containing(meth)acrylic esters.

SUMMARY OF THE INVENTION

[0011] The present inventors made investigations in various ways insearch for means of improving the stability of vinyl ethergroup-containing (meth)acrylic esters, which have both radicalpolymerizability and cation polymerizability and, as a result, foundthat by causing a radical polymerization inhibitor to coexist with vinylether group-containing (meth)acrylic esters, it is possible to improvethe stability of vinyl ether group-containing (meth)acrylic esters whilepreventing the polymerization thereof during storage or handling withoutimpairing polymerizability of vinyl ether group-containing (meth)acrylicesters. They also found that when a basic compound is further caused tocoexist on that occasion, the stability of vinyl ether group-containing(meth)acrylic esters can be more improved. Thus, they realized that byemploying such compositions, it becomes possible to improve the storagestability and stability in handling thereof simply and economically tothereby render vinyl ether group-containing (meth)acrylic esters suitedfor a wide range of industrial use. Hereinafter, these compositions aresometimes referred to as stabilized vinyl ether group-containing(meth)acrylic ester compositions.

[0012] It is considered that vinyl ether group-containing (meth)acrylicesters are polymerized when, during storage or handling, (1) radicalsare formed as a result of abstraction of hydrogen atoms on carbon atomsadjacent to vinyl ether groups or (2) radicals are formed as a result offormation of ether peroxides from vinyl ether groups. In these cases, itis meant that vinyl ether group-containing (meth)acrylic esters involvedin radical formation act as initiators. The above-mentioned case (2)maybe avoided by replacing the atmosphere with nitrogen and, on thisoccasion, esters are to be handled in an atmosphere containing molecularoxygen to prevent polymerization of (meth)acryloyl groups due to free ofoxygen. On the other hand, with vinyl ethers other than (meth)acrylicesters or with vinyl ether group-free (meth)acrylic esters, such anevent as mentioned above under (1) or (2) generally will not occur.Thus, as compared with these, vinyl ether group-containing (meth)acrylicesters have insufficient stability. While those (meth)acrylic esterswhich have ether groups may exceptionally form radicals as a result ofabstraction of hydrogen atoms on carbon atoms adjacent to ether groups,the rate of hydrogen atom abstraction in vinyl ether group-containing(meth)acrylic esters is much faster and, even when compared with such(meth)acrylic esters, vinyl ether group-containing (meth)acrylic estersare insufficient in stability.

[0013] The present inventors paid their attention to these causesleading to decreased stability of vinyl ether group-containing(meth)acrylic esters and found that the problems mentioned above can besolved successfully by the above-mentioned contrivances that have so farnever been made. In an aspect, such finding has led to completion of thepresent invention.

[0014] The inventors further made investigations concerning how tohandle vinyl ether group-containing (meth)acrylic esters and, as aresult, found (1) that when the water concentration in the liquid phasecontaining vinyl ether group-containing (meth)acrylic esters isexcessively high, vinyl ether groups tend to be decomposed or the estermoiety hydrolyzed and (meth)acrylic acids formed upon this hydrolysismay possibly cause polymerization of vinyl ether groups and (2) thatwhen the oxygen concentration in the gaseous phase in contact with vinylether group-containing (meth)acrylic esters is excessively low,(meth)acryloyl groups undergo polymerization due to free of oxygen and,when the oxygen concentration in the gaseous phase is excessively high,vinyl ether groups are deteriorated. They thus realized that byrestricting the water concentration in the liquid phase containing vinylether group-containing (meth)acrylic esters and/or the oxygenconcentration in the gaseous phase in contact with vinyl ethergroup-containing (meth)acrylic esters to a specific range, it becomespossible to handle vinyl ether group-containing (meth)acrylic esters ina stable manner.

[0015] Furthermore, they found (3) that vinyl ether group-containing(meth)acrylic esters easily, because of their easy polymerizability,undergo quality deterioration due to polymerization and/or decompositionwhen subjected to irradiation with light, in particular visible raysand/or ultraviolet rays and (4) that the quality deterioration due topolymerization or decomposition upon light irradiation is influenced bymolecular oxygen. They thus realized that by handling vinyl ethergroup-containing (meth)acrylic esters in lightproof structures, it isalso possible to handle the same in a stable condition and that byrestricting the molecular oxygen concentration in the gaseous phasewithin lightproof structures, it is possible to handle esters in a morestable condition.

[0016] They made further investigations concerning methods of producingvinyl ether group-containing (meth)acrylic esters and, as a result,found that when, in the method of producing vinyl ether group-containing(meth)acrylic esters by subjecting hydroxyl group-containing vinylethers and (meth)acrylic esters to transesterification reaction,hydroxyl group-containing vinyl ether compositions containing specificimpurities, not completely pure hydroxyl group-containing vinyl ethers,are used as raw materials, the desired esters can be produced in aneconomic manner and the by product lower alcohol can be removed moreeasily than in the case where pure hydroxyl group-containing vinylethers are used as raw materials and, thus, the time required for theproduction of vinyl ether group-containing (meth)acrylic esters can beshortened. In addition, they found that when, in carrying out thetransesterification reaction, the water content or oxygen concentrationin the reaction system is restricted to a specific range and/or thereaction is carried out in lightproof structures, vinyl ethergroup-containing (meth)acrylic esters can be produced stably in a simpleand economical manner while inhibiting polymerization. The “timerequired for the production” so referred to herein means the time fromthe point of initiation of temperature raising in the reaction system tothe point when the yield of vinyl ether group-containing (meth)acrylicesters becomes constant as indicated by analysis of the reaction systemusing gas chromatography.

[0017] They also found that when, in purifying vinyl ethergroup-containing (meth)acrylic esters produced, the purification iscarried out in an atmosphere such that the molecular oxygenconcentration in the gaseous phase in the purification system is withina specific range, or in lightproof structures, esters can be purifiedstably in a simple and economical manner while preventing the formationof impurities due to polymerization and decomposition duringpurification. Such findings have led to completion of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] A vinyl ether group-containing (meth)acrylic ester compositionand a method of producing the same according to the present inventionare described in the following.

[0019] The vinyl ether group-containing (meth)acrylic ester compositionin the present invention comprises causing a radical polymerizationinhibitor, or both of a radical polymerization inhibitor and a basiccompound, to coexist with a vinyl ether group-containing (meth)acrylicester represented by the following general formula (1):

CH₂═CR¹—COO—R²—O—CH═CH—R³  (1)

[0020] in the formula, R¹ represents a hydrogen atom or a methyl group,R² represents an organic residue and R³ represents a hydrogen atom or anorganic residue.

[0021] The vinyl ether group-containing (meth)acrylic esters in thepresent invention are compounds represented by the general formula (1)and having specific structures containing a vinyl ether grouprepresented by —O—CH═CH—R³ and a (meth)acryloyl group represented byCH₂═CR¹—COO— within one molecule. In the practice of the presentinvention, such compounds may be used singly or two or more of them maybe used in combination.

[0022] In the practice of the present invention, the vinyl ethergroup-containing (meth)acrylic esters represented by the general formula(1) may be those compounds in which the substituent represented by R¹ isa hydrogen atom or a methyl group, the substituent represented by R² isan organic residue and the substituent represented by R³ is a hydrogenatom or an organic residue.

[0023] In the present specification, the term “organic residues” as usedherein in defining compounds represented by the general formula meansorganic groups bound to the fundamental structures constituting thesecompounds.

[0024] The organic residues represented by R² in the above generalformula (1) are preferably, for example, straight, branched or cyclicalkylene groups containing 2 to 20 carbon atoms, alkylene groupscontaining 2 to 20 carbon atoms and having at least one oxygen atom inthe form of an ether linkage and/or an ester linkage within thestructure thereof, and aromatic groups which contain 6 to 11 carbonatoms and may optionally be substituted. Among them, alkylene groupscontaining 2 to 6 carbon atoms and alkylene groups containing 4 to 10carbon atoms and having at least one oxygen atom in the form of an etherlinkage are preferred.

[0025] The organic residues represented by R³ in the above generalformula (1) are preferably, for example, straight, branched or cyclicalkyl groups containing 1 to 10 carbon atoms and aromatic groups whichcontain 6 to 11 carbon atoms and may optionally be substituted. Amongthem, alkyl groups containing 1 to 2 carbon atoms and aromatic groupscontaining 6 to 8 carbon atoms are preferred.

[0026] As typical examples of vinyl ether group-containing (meth)acrylicesters represented by the above general formula (1), specifically, thefollowing ones are preferred: 2-Vinyloxyethyl (meth)acrylate,3-vinyloxypropyl (meth)acrylate, 1-methyl-2-vinyloxyethyl(meth)acrylate, 2-vinyloxypropyl (meth)acrylate, 4-vinyloxybutyl(meth)acrylate, 4-vinyloxycyclohexyl (meth)acrylate, 6-vinyloxyhexyl(meth)acrylate, 4-vinyloxymethylcyclohexylmethyl (meth)acrylate,2-(vinyloxyethoxy)ethyl (meth)acrylate and 2-(vinyloxyethoxyethoxy)ethyl(meth)acrylate.

[0027] In the practice of the present invention, methods of producingvinyl ether group-containing (meth)acrylic esters represented by thegeneral formula (1) are preferably, for example, the method comprisingsubjecting a (meth)acrylic acid and a hydroxyl group-containing vinylether to esterification (method A), the method comprising subjecting a(meth)acrylic acid halide and a hydroxyl group-containing vinyl ether toesterification (method B), the method comprising subjecting a(meth)acrylic anhydride and a hydroxyl group-containing vinyl ether toesterification (method C), the method comprising subjecting a(meth)acrylic ester and a hydroxyl group-containing vinyl ether totransesterification (method D), the method comprising subjecting a(meth)acrylic acid and a halogen-containing vinyl ether toesterification (method E) and the method comprising subjecting a(meth)acrylic acid alkali (or alkaline earth) metal and ahalogen-containing vinyl ether to esterification (method F). Among them,the method comprising subjecting a (meth)acrylic ester and a hydroxylgroup-containing vinyl ether to transesterification (method D) ispreferred. On that occasion, the method of producing a vinyl ethergroup-containing (meth)acrylic ester which is mentioned later herein ispreferably applied.

[0028] In accordance with the present invention, stabilized vinyl ethergroup-containing (meth)acrylic ester compositions can be obtained bycausing a radical polymerization inhibitor, or both of a radicalpolymerization inhibitor and a basic compound, to coexist with the abovevinyl ether group-containing (meth)acrylic esters. The radicalpolymerization inhibitor and basic compound may each be used singly or acombination of two or more species.

[0029] As methods of producing vinyl ether group-containing(meth)acrylic ester compositions according to the present invention, (1)the method comprising adding a predetermined amount of a radicalpolymerization inhibitor, or a predetermined amount of a radicalpolymerization inhibitor and a predetermined amount of a basic compound,to the above vinyl ether group-containing (meth)acrylic ester, (2) themethod comprising adding the vinyl ether group-containing (meth)acrylicester to a predetermined amount of a radical polymerization inhibitor,or a predetermined amount of a radical polymerization inhibitor and apredetermined amount of a basic compound, and (3) the method comprisinga combination of the above two methods are preferred. Such a productionmethod, namely the method of causing a radical polymerization inhibitor,or both of a radical polymerization inhibitor and a basic compound, tocoexist with the vinyl ether group-containing (meth)acrylic esterrepresented by the above general formula (1), also constitutes an aspectof the present invention.

[0030] The radical polymerization inhibitors to be used in accordancewith the invention maybe those radical polymerization inhibitors ingeneral use. Specifically, there may be preferably mentioned quinonetype polymerization inhibitors such as hydroquinone,methoxyhydroquinone, benzoquinone and p-tert-butylcatechol; alkylphenoltype polymerization inhibitors such as 2,6-di-tert-butylphenol,2,4-di-tert-butylphenol, 2-tert-butyl-4,6-dimethylphenol,2,6-di-tert-butyl-4-methylphenol and 2,4,6-tri-tert-butylphenol; aminetype polymerization inhibitors such as alkylated diphenylamine,N,N′-diphenyl-p-phenylenediamine, phenothiazine,4-hydroxy-2,2,6,6-tetramethylpiperidine,4-benzoyloxy-2,2,6,6-tetramethylpiperidine,1,4-dihydroxy-2,2,6,6-tetramethylpiperidine and1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine; copperdithiocarbamate type polymerization inhibitors such as copperdimethyldithiocarbamate, copper diethyldithiocarbamate and copperdibutyldithiocarbamate; N-oxyl type polymerization inhibitors such as2,2,6,6-tetramethylpiperidine-N-oxyl,4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl,4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl and esters of4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl; etc. Among these,quinone type polymerizaiton inhibitors, amine type polymerizationinhibitors, copper dithiocarbamate type polymerization inhibitors andN-oxyl type polymerization inhibitors are preferred radicalpolymerization inhibitors. Particularly preferred radical polymerizationinhibitors are hydroquinone, methoxyhydroquinone, benzoquinone,p-tert-butylcatechol, phenothiazine, alkylateddiphenylamine, copperdibutyldithiocarbamate, 2,2,6,6-tetramethylpiperidine-N-oxyl,4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, esters of4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, and the like.

[0031] The level of addition of the above radical polymerizationinhibitors may vary according to the species of the vinyl ethergroup-containing (meth)acrylic ester represented by the general formula(1) but preferably is not less than 0.00001% by weight, more preferablynot less than 0.0001% by weight, still more preferably not less than0.0002% by weigh, particularly preferably not less than 0.0005% byweight, but preferably not more than 5% by weight, more preferably notmore than1% by weight, still more preferably not more than 0.5% byweight, particularly preferably not more than 0.1% by weight, relativeto said vinyl ether group-containing (meth)acrylic esters. The aboverange of the radical polymerization inhibitor addition level ispreferred from the viewpoint of polymerization inhibition and economy.

[0032] The basic compounds to be used in accordance with the presentinvention are preferably, for example, alkali (alkaline earth) metalhydroxides such as lithium hydroxide, sodium hydroxide, potassiumhydroxide, cesium hydroxide, magnesium hydroxide and calcium hydroxide;alkali (alkaline earth) metal carbonate salts such as lithium hydrogencarbonate, sodium hydrogen carbonate, potassium hydrogen carbonate,cesium hydrogen carbonate, magnesium hydrogen carbonate, calciumhydrogen carbonate, lithium carbonate, sodium carbonate, potassiumcarbonate, cesium carbonate, magnesium carbonate and calcium carbonate;alkali (alkaline earth) metal carboxylate salts such as lithium acetate,sodium acetate, potassium acetate, cesium acetate, magnesium acetate andcalcium acetate; alkali (alkaline earth) metal alkoxides such as sodiummethoxide, sodium ethoxide, sodium butoxide, potassium methoxide,potassium ethoxide, potassium butoxide and calcium ethoxide; amines suchas ammonia, methylamine, ethylamine, butylamine, ethanolamine,dimethylamine, diethylamine, dibutylamine, diethanolamine,trimethylamine, triethylamine, tributylamine, tris(2-ethylhexyl)amine,triethanolamine, ethylenediamine, tetramethylethylenediamine, tren,1,4-diazabicyclo[2,2,2]octane, aniline, methylaniline, dimethylaniline,pyridine, piperidine, picoline, N,N-dimethyl-p-toluidine, lutidine,quinoline, isoquinoline and collidine; etc. Preferred among these basiccompounds are alkali (alkaline earth) metal hydroxides and amines.Particularly preferred basic compounds are sodium hydroxide, potassiumhydroxide, tris(2-ethylhexyl)amine, tributylamine and triethanolamine.

[0033] The level of addition of the above basic compounds may varyaccording to the species of the vinyl ether group-containing(meth)acrylic ester represented by the general formula (1) butpreferably is not less than 0.00001% by weight, more preferably not lessthan 0.0001% by weight, still more preferably not less than 0.0002% byweigh, particularly preferably not less than 0.0005% by weight, butpreferably not more than 5% by weight, more preferably not more than 1%by weight, still more preferably not more than 0.5% by weight,particularly preferably not more than 0.1% by weight, relative to saidvinyl ether group-containing (meth)acrylic esters. The above range ofthe basic compound addition level is preferred from the viewpoint ofpolymerization inhibition and economy.

[0034] By causing radical polymerization inhibitors, or both of radicalpolymerization inhibitors and basic compounds, to coexist with vinylether group-containing (meth)acrylic esters represented by the generalformula (1) in accordance with the present invention, it becomespossible to stabilize the above esters more effectively. The ratiobetween the radical polymerization inhibitor and basic compound on thatoccasion may be such that each are used at an addition level within therange mentioned above.

[0035] The compositions of the present invention, namely “the vinylether group-containing (meth)acrylic esters and the radicalpolymerization inhibitors”, or “the vinyl ether group-containing(meth)acrylic esters together with the radical polymerization inhibitorsand the basic compounds” may be used together with other components suchas additives, organic solvents and the like.

[0036] In such cases, the ratio of other components is preferably notless than 50% by weight, more preferably not less than 70% by weight,still more preferably not less than 80% by weight, particularlypreferably not less than 90% by weight, most preferably not less than95% by weight, relative to the total amount of the composition.

[0037] The method of handling vinyl ether group-containing (meth)acrylicesters according to the present invention is now described.

[0038] The method of handling vinyl ether group-containing (meth)acrylicesters according to the invention is preferably (a) the mode in whichthe water concentration in a liquid phase containing the vinyl ethergroup-containing (meth)acrylic ester represented by the above generalformula (1) is at a level not higher than 15% by weight, (b) the mode inwhich the molecular oxygen concentration in the gaseous phase in contactwith the vinyl ether group-containing (meth)acrylic ester represented bythe above general formula (1) is at a level of 0.01 to 15% by volume,(c) the mode in which the vinyl ether group-containing (meth)acrylicester represented by the above general formula (1) is handled in alightproof structure or (d) the mode in which the vinyl ethergroup-containing (meth)acrylic ester represented by the above generalformula (1) is handled in a lightproof structure while keeping themolecular oxygen concentration in the gaseous phase within saidlightproof structure at 0.01 to 22% by volume. It is also possible toappropriately combine the modes (a), (b), (c) and (d).

[0039] The term “handling” as used in the present invention means thetransportation of the vinyl ether group-containing (meth)acrylic estersin tank lorries or the like; the storage in tanks, containers or thelike; transfer through piping including pipes, valves, nozzles, etc.;and mixing and stirring in reaction vessels, reaction apparatuses,tanks, containers or the like. These operations may be conducted singlyor two or more of them may be conducted in appropriate combination.

[0040] In handling the vinyl ether group-containing (meth)acrylic estersof the general formula (1) according to the present invention, it ispreferred that radical polymerization inhibitors, or both of radicalpolymerization inhibitors and basic compounds be caused to coexist withthe esters. As the radical polymerization inhibitors and basiccompounds, there may respectively be used those specifically mentionedhereinabove.

[0041] The level of addition of the above radical polymerizationinhibitors may vary according to the species of the vinyl ethergroup-containing (meth)acrylic ester represented by the above generalformula (1) but preferably is not less than 0.0001% by weight, morepreferably not less than 0.0005% by weight, still more preferably notless than 0.001% by weigh, particularly preferably not less than 0.002%by weight, but preferably not more 5% by weight, more preferably notmore 1% by weight, particularly preferably not more than 0.1% by weight,relative to said vinyl ether group-containing (meth)acrylic esters. Theabove range of the radical polymerization inhibitor addition level ispreferred from the viewpoint of yield, polymerization inhibition andeconomy.

[0042] The level of addition of the above basic compounds may varyaccording to the species of the vinyl ether group-containing(meth)acrylic ester represented by the general formula (1) butpreferably is not less than 0.00001% by weight, more preferably not lessthan 0.0001% by weight, still more preferably not less than 0.0002% byweigh, particularly preferably not less than 0.0005% by weight, butpreferably not more than 5% by weight, more preferably not more1% byweight, still more preferably not more than 0.5% by weight, particularlypreferably not more than0.1% by weight, relative to the vinyl ethergroup-containing (meth)acrylic esters. The above range of the basiccompound addition level is preferred from the viewpoint of yield,polymerization inhibition and economy.

[0043] In cases where the above radical polymerization inhibitors andbasic compounds are caused to coexist with the esters, the ratio betweenthe radical polymerization inhibitor and basic compound may be such thateach are used at an addition level within the range mentioned above.

[0044] In handling vinyl ether group-containing (meth)acrylic esters inthe above-mentioned mode (a), the water concentration in the liquidphase, namely in the liquid phase containing vinyl ethergroup-containing (meth)acrylic esters represented by the above generalformula (1), is adjusted within a specific range. The waterconcentration in the liquid phase is not more than 15% by weight,preferably not more than 5% by weight, more preferably not more than 3%by weight, still more preferably not more than 1%, particularlypreferably not more than 0.5% by weight. The above water concentrationrange is preferred from the viewpoint of stable handling.

[0045] For adjusting the water concentration in the above liquid phaseto not more than 15% by weight in the production of vinyl ethergroup-containing (meth)acrylic esters, the following methods arepreferred: the method comprising storing them promptly afterpurification by distillation or washing with water-insoluble solvents;the method comprising bubbling dried inert gas, such as nitrogen orargon and mixed gas composed of such inert gas and oxygen through theesters at room temperature or under warming conditions; the methodcomprising drying the esters with dehydrating agents such as molecularsieve, calcium chloride, magnesium sulfate, calcium sulfate or potassiumcarbonate, etc. These methods may appropriately be used in combination.

[0046] In handling vinyl ether group-containing (meth)acrylic esters inthe above-mentioned mode (b), the molecular oxygen concentration in thegaseous phase, namely in the gaseous phase in contact with the vinylether group-containing (meth)acrylic esters, is adjusted within aspecific range. The molecular oxygen concentration in the gaseous phaseis 0.01 to 15% by volume, preferably not lower than 0.02% by volume,more preferably not lower than 0.05% by volume, but preferably nothigher than 12% by volume, more preferably not higher than 10% byvolume. The above molecular oxygen concentration range is preferred fromthe viewpoint of stable handling and economy.

[0047] The “gaseous phase (gaseous phase in contact with the vinyl ethergroup-containing (meth)acrylic ester)” means the gaseous phase incontainers or structures, such as tank lorries or tanks, with the vinylether group-containing (meth)acrylic esters placed therein for handling.

[0048] As for the method of adjusting the molecular oxygen concentrationin the above gaseous phase to 0.01 to 15% by volume, for example, themethod comprising blowing inert gas, such as nitrogen or argon, into thegaseous phase and/or liquid phase and the method comprising blowingmixed gas composed of inert gas and oxygen into the gaseous phase and/orliquid phase are preferred.

[0049] Furthermore, in accordance with the present invention, it ispreferred from the viewpoint of stable handling and economy that, inhandling the vinyl ether group-containing (meth)acrylic esters, themolecular oxygen concentration in the above gaseous phase be adjusted to0.01 to 15% by volume and the water concentration in the liquid phasecontaining the vinyl ether group-containing (meth)acrylic ester beadjusted to not higher than 15% by weight. In this case, the adjustmentmethods, the preferred molecular oxygen concentration range and thepreferred water concentration range are the same as mentioned above.

[0050] In handling vinyl ether group-containing (meth)acrylic esters inthe above-mentioned mode (c), handling them in lightproof structuresmakes stable handling possible.

[0051] The “lightproof structures” used in handling according to thepresent invention are structures made of lightproof materials, such asstructures for transportation for example tank lorries; structures forstorage for example tanks, drums, bottles and cans; structures fortransfer for example pipes, nozzles and valves; and structures formixing and stirring for example reaction vessels, tanks and containers;etc. The portion of the inside surface area of the structure to whichlight can reach is preferably not more than 20%, more preferably notmore than 15%, still more preferably not more than 10%, particularlypreferably not more than 8%, of the whole inside surface area of thestructure. The “lightproof materials” as so referred to herein arematerials substantially impermeable to light (visible rays, ultravioletrays and infrared rays). Furthermore, the structure inside surfaceportion to which light can reach or the structure inside surface portionto which light cannot reach may be continuous or discontinuous.

[0052] The lightproof materials mentioned above include, for example, aspreferred species, iron and steel such as industrial pure iron, carbonsteel (JISG-SS, JISG-SC, JISG-SB, JISG-SM, JISG-SGP, JISG-STGP,JISG-STS, JISG-STB, JISG-STL, JISG-STKM, JISG-SWR, JISG-SK, JISG-SF,JISG-SC, etc.), cast iron (JISG-FC, JISG-FCD, JISG-FCM, etc.), low-alloysteeel (JISG-SNC, JISG-SNCM, JISG-SCr, JISG-SCM, JISG-SACM, JISG-SCA,etc.), low-alloy cast iron (nitensil, nihard, acicular, etc.),low-nickel steel (JISG-STPL, JISG-STBL, JES-Ni, ASTM-A203, etc.), nickelsteel (ASTMA353, etc.), chrome stainless steel (JISG-SUH1, JISG-SUH2,JISG-SUH3, AISI-TP501, AISI-TP503, etc.), etc.; high silicon cast iron;high nickel cast iron such as 15% Ni cast iron (Ni-Resist1, etc.), 20%Ni cast iron (Ni-Resist2, etc.), 30% Ni cast iron (Ni-Resist3, etc.),etc.; high chromium steel such as high Cr cast iron (Nirosta, etc.),high Cr—Mo cast iron, etc.

[0053] Further includes martensitic stainless steel such as 13 Crsteel(SUS403, SUS410, SUS414, SUS416, etc.), 13Cr steel (SUS420, etc.),16Cr2Ni steel (SUS431, SUS440A, SUS440B, SUS440C, etc.), etc.; ferriticstainless steel such as 18 Cr steel (SUS420, etc.), 25Cr steel (SUS446,etc.), 13Cr—Al steel (SUS405, etc.), etc.; austenitic stainless steelsuch as 18-8 steel (SUS301, SUS302, SUS303, SUS304, SUS305, SUS308,SUS321, SUS347, etc.), 18-8L steel (SUS304L, etc.), 18-8Mo steel(SUS316, SUS317, etc.), 18-8MoL steel (SUS316L, etc.), 22Cr-12Ni steel(SUS309, SUS309S, etc.), 25Cr-20Ni steel (SUS310, SUS310S, SUS314,etc.), etc.; special austenitic stainless steel such as 20 alloys(Worthite, Durimet20, Carpenter20, Aloyco20, FA20, etc.), HN alloys(Chromax, etc.), etc.; Fe—Cr—Al alloys such as Fe—Cr—Al—Si alloys(Sicromal8, Sicromal9, Sicromal10, Sicromal11, Sicromal12, etc.),Fe—Cr—Al—Co alloys (KanthalA, etc.), etc.; high manganese steel such asJIS-SCMnH, etc.; copper and copper alloys such as industrial pure copper(JIS-CuP, JIS-CuB, JIS-CuT, JIS-DCuP, JIS-DCuT, etc.), Cu—Al alloys(JIS-ABP, JIS-ABB, JIS-BsTF, aluminum bronze, aluminum brass, etc.),Cu—Si alloys (JIS-SiBT, JIS-SzBC, siliconbronze, Everdur, ARalloys,Silzinbronze, etc.), Cu—Sn-P alloys (JIS-PBP, JIS-PBS, JIS-PBB, JIS-PBC,phosphor bronze, etc.), Cu—Sn—Zn alloys (JIS-BsC, bronze casting, etc.),Cu—Zn alloys (JIS-NBsP, etc.), Cu—Zn—Sn alloys (Red-Brass, etc.), Cu—Znalloys (JIS-BsP, JIS-LBC, JIS-RBsP, brass, leadedbrass, redbrass, etc.),etc.; Cu—Ni alloys such as Cu—Ni 20 (cupro-nickel, JIS-CNTF2, etc.),Ni—Ag (nickel silver, German silver, JIS-NSP, JIS-SNP1, etc.), Cu—Ni 30(cupro-nickel, JIS-CNTF3, JIS-CNP3, etc.), etc.; aluminum and aluminumalloys such as industrial pure aluminum (JIS-AlP, JIS-AlR, JIS-AlB,JIS-AlV, JIS-AlW, JIS-AlT, ALCOA-EC, ALCOA-1050, ALCOA-1060, ALCOA-1100,ALCOA-1130, ALCOA-1175, ALCOA-1260, etc.), highlypure aluminum, Al—Mnalloys (JIS-A2P3, JIS-A2T3, ALCOA-3003, etc.), high-tensile aluminumalloys (JIS-A3P, JIS-A3R, JIS-A3T, JIS-A3B, JIS-A3W, ALCOA-2014,ALCOA-2017, ALCOA-2024, ALCOA-2025, Duralumin, Super Duralumin, Yalloys, etc.), Al—Mg—Si alloys (JIS-A4F, ALCOA-6061, etc.), Al—Si alloys(JIS-AC3A, JIS-AC4ABC, ALCOA-4032, silumin casting, etc.), Al—Mg alloys(JIS-corrosion protected aluminum alloy Type 1, JIS-corrosion protectedaluminum alloy Type 2, JIS-corrosion protected aluminum alloy Type 7,ALCOA-5052, ALCOA-5056, ALCOA-5083, etc.), etc.; magnesium and magnesiumalloys such as industrial pure magnesium, magnesium alloys (JIS-MC,Dowmetal, Elektron, etc.), etc.; nickel such as industrial pure nickel(JIS-VNiP, JIS-VCNiP, JIS-VNiW, JIS-VCNiT, ASTM-B39, ASTM-160, ASTM-161,ASTM-162, etc.), etc.; Ni—Cr—Fe alloys such as 27A (Inconel, Colmonoy6,etc.), 27B (Incone1600, ASTM-B163, ASTM-B166, ASTM-B167, ASTM-B168,etc.), 27C, etc.; Ni—Cu alloys such as Monel (JIS-NCuT, JIS-NCuP,ASTM-B127, ASTM-B163, ASTM-B164, ASTM-B165, Monel 400, etc.), K Monel,etc.; Ni—Mo—Fe—Cr alloys such as 30A (HastelloyA, Contracid, etc.), 30B(ASTM-B333, ASTM-B335, ASTM-B494, HastelloyB, Chlorimet2, etc.), 30C(ASTM-B336, ASTM-B494, HastelloyC, Chlorimet3, etc.), 30D (HastelloyN,etc.), 30E (HastelloyF, etc.), 30F (Ni-o-nel, etc.), 30G (R-55, etc.),etc.; Ni—Cr—Cu—Mo alloys such as 31A (IlliumG, etc.), 31B (Illium98,etc.); Ni—Si alloys such as HastelloyD, etc.; cobalt alloys such asCo—Cr alloys (Stelite21, Stelite23, Stelite27, Stelite31, etc.),Co—Cr—Ni alloys (Haynes25, Haynes36, etc.), Co—Si alloys, etc.; lead andlead alloys such as industrial pure lead (JIS-PbP, JIS-PbT, JIS-PbTW,ASTM-B29, ASTM-B325, etc.), lead telluride, hard lead (JIS-HPbP,JIS-HPbT, ASTM-B23, ASTM-B32, etc.), homogen lead fusion lining, etc.;tin; zinc and zinc alloys such as industrial pure zinc (JIS-zinc plate,ASTM-B6, etc.), zinc alloys (ASTM-B69, etc.), etc.; precious metals suchas silver, gold, platinum, niobium, tantalum (ASTM-B364, ASTM-B365,etc.) and platinum group and vanadium group metals; tungsten; titaniumand titanium alloys such as industrial pure titanium (JIS-TP, JIS-TTP,JIS-TB, JIS-TW, ASTM-B265, ASTM-B337, ASTM-B338, ASTM-B348, ASTM-B299,ASTM-B367, ASTM-B381, etc.), titanium alloys (ASTM-B265, ASTM-B348,ASTM-B367, ASTM-B381, etc.), etc.; zirconium and zirconium alloys suchas zirconium (ASTM-B349, ASTM-B350, ASTM-B351, ASTM-B352, ASTM-B353,ASTM-B356, etc.), zirconium alloys (Zircaloy-1, Zircaloy-2, Zircaloy-3,ASTM-B350, ASTM-B351, ASTM-B352, ASTM-B353, ASTM-B356, etc.), etc.;molybdenum such as ASTM-B384,ASTM-B385,ASTM-B386,ASTM-B387, etc.;chromium such as ASTM-B383, ASTM-B391, ASTM-B392, ASTM-B393, ASTM-B394,etc.; silicate products such as porcelain, earthenware, liparite,acid-resistant bricks, acid-resistant tiles, acid-resistant porcelain,silica cement, fire bricks, refractory mortar, vitreous enamel, etc.;concrete; sulfur cement; carbon and graphite products such as carbonformed products, graphite formed products, impervious carbon, imperviousgraphite, etc.; asbestos; synthetic resins such as opaque vinylidenechloride resin, opaque phenol resin, opaque furan resin, opaque vinylchloride resin, opaque ethylene tetrafluoride, opaque ethylenetrifluoride, opaque silicate resin, opaque polyethylene, opaquepolyisobutylene, opaque polystyrene, opaque epoxy resin, opaqueunsaturated polyester, opaque polyamide resin, opaque chlorinatedpolyether resin, opaque polycarbonate resin, opaque polyurethane resin,opaque urea resin, opaquemelamine resin, etc.; asphalt; natural rubberand synthetic rubber such as opaque natural rubber, opaque naturalrubber hydrochloride or chlorinated natural rubber, opaque nitrilerubber, opaque styrene rubber, opaque butadiene-isobutylene syntheticrubber, opaque polychloroprene, opaque asbestos-filled rubber sheet,opaque butyl rubber, opaque polysulfide rubber, opaque chlorosulfonatedpolyethylene rubber, opaque fluorine rubber, opaque silicone rubber,opaque urethane rubber, etc.; glass such as glass of which inside and/oroutside is coated with opaque synthetic resin, glass of which insideand/or outside is coated with natural rubber or synthetic rubber, glassof which inside and/or outside is coated with metal, glass of whichinside and/or outside is plated with metal, etc.

[0054] Among these, iron and steel, high silicon cast iron, high nickelcast iron, high chromium steel, martensitic stainless steel, ferriticstainless steel, austenitic stainless steel, special austeniticstainless steel, Fe—Cr—Al alloys, high manganese steel, copper andcopper alloys, Cu—Ni alloys, aluminum and aluminum alloys, magnesium andmagnesium alloys, nickel, Ni—Cr—Fe alloys, Ni—Cu alloys, Ni—Mo—Fe—Cralloys, Ni—Cr—Cu—Mo alloys, Ni—Si alloys, cobalt alloys, lead and leadalloys, tin, zinc and zinc alloys, tungsten, titanium and titaniumalloys, zirconium and zirconium alloys, molybdenum and chromium are morepreferred as the lightproof material. These lightproof materials can beused singly or two or more of them may be used in combination.

[0055] In handling a vinyl ether group-containing (meth)acrylic esterrepresented by the above general formula (1) in the above mode (d), theester is handled in a lightproof structure in an atmosphere such that amolecular oxygen concentration in the gaseous phase within the structureof 0.01 to 22% by volume, whereby quality degradation due topolymerization or decomposition can effectively be prevented and thevinyl ether group-containing (meth)acrylic ester can be handled in amore stable manner.

[0056] The molecular oxygen concentration in the gaseous phase withinthe above structures is preferably not lower than 0.02% by volume,particularly preferably not lower than 0.05% by volume, but preferablynot higher than 18% by volume, particularly preferably not higher than15% by volume. If the molecular oxygen concentration in the gaseousphase within the structures is lower than 0.01% by volume, vinyl ethergroup-containing (meth)acrylic esters may undergo polymerization due tofree of oxygen. If the molecular oxygen concentration in the gaseousphase within the structures is higher than 22% by volume, qualitydegradation may occur due to polymerization or decomposition. Therefore,the above molecular oxygen concentration range is preferred from theviewpoint of quality, polymerization inhibition and economy.

[0057] It is necessary to handle the esters in lightproof structuressince the quality degradation due to polymerization or decompositionmentioned above is accelerated in optically transparent structures.

[0058] Available for use in adjusting the molecular oxygen concentrationin the gaseous phase within the above structures to a specific range are(a) the method comprising feeding molecular oxygen or a gas containingmolecular oxygen, such as air, and an inert gas, such as nitrogen orargon, respectively to the structure and (b) the method comprisingadmixing molecular oxygen or a molecular oxygen-containing gas, such asair, with an inert gas, such as nitrogen or argon, in advance and thenfeeding the mixture to the structure, and the like. As for the gasfeeding method, the gases or gas mixture is fed to one or both of theliquid phase and gaseous phase either continuously or intermittently. Asfor the method of maintaining the molecular oxygen concentration in thegaseous phase in the structure within a specific range, the continuousor intermittent feeding method and the method comprising initialatmosphere substitution, followed by tight closure are preferred.

[0059] In handling vinyl ether group-containing (meth)acrylic estersrepresented by the above general formula (1), the handling temperatureis, specifically, preferably not lower than −20° C., more preferably notlower than −15° C., still more preferably not lower than −5° C.,particularly preferably not lower than 0° C. Conversely, it ispreferably not higher than 125° C., more preferably not higher than 100°C., still more preferably not higher than 80° C., particularlypreferably not higher than 60° C. The handling pressure may be atordinary pressure (atmospheric pressure), under pressure or underreduced pressure.

[0060] The method of producing a vinyl ether group-containing(meth)acrylic ester according to the present invention is described inthe following.

[0061] The method of producing a vinyl ether group-containing(meth)acrylic ester is a method of producing a vinyl ethergroup-containing (meth)acrylic ester represented by the above generalformula (1). The above method of producing a vinyl ethergroup-containing (meth)acrylic ester comprises reacting a hydroxylgroup-containing vinyl ether represented by the following generalformula (2):

R³—CH═CH—O—R²—OH  (2)

[0062] in the formula, R² represents an organic residue and R³represents a hydrogen atom or an organic residue,

[0063] with a (meth)acrylic ester represented by the following generalformula (3):

CH₂═CR¹—COOR⁴  (3)

[0064] in the formula, R¹ represents a hydrogen atom or a methyl groupand R⁴ represents an organic residue,

[0065] and in which the above hydroxyl group-containing vinyl ethercontains at least one compound selected from the group consisting of adivinyl ether represented by the following general formula (4):

R³—CH═CH—O—R²—O—CH═CH—R³  (4)

[0066] in the formula, R² represents an organic residue and the twoR³groups are the same or different and each represents a hydrogen atomor an organic residue, a 2-substituted-1,3-dioxo compound represented bythe following general formula (S):

[0067] in the formula, R²represents an organic residue and R³ representsa hydrogen atom or an organic residue,

[0068] and an unsaturated bond-containing vinyl ether represented by thefollowing general formula (6):

R³—CH═CH—O—R⁵  (6)

[0069] in the formula, R³ represents a hydrogen atom or an organicresidue; R⁵ represents an organic residue containing an unsaturated bondrepresented by —CR⁶═CR⁷—; and R⁶ and R⁷ are the same or different andeach represents a hydrogen atom or an organic residue. In the presentspecification, such production method is referred to as the productionmethod (a).

[0070] In the above production method (a), vinyl ether group-containing(meth)acrylic esters can be produced economically by using hydroxylgroup-containing vinyl ether compositions containing at least onecompound selected from the group consisting of divinyl ethersrepresented by the above general formula (4), 2-substituted-1,3-dioxocompounds represented by the above general formula (5) and unsaturatedbond-containing vinyl ethers represented by the above general formula(6) as a raw material (raw material composition) without using anentirely pure hydroxyl group-containing vinyl ether as a raw materialand, by using such hydroxyl group-containing vinyl ether compositions,it becomes possible to remove the by product lower alcohols more easilyand curtail the time for producing the vinyl ether group-containing(meth)acrylic esters as compared with the case of using the entirelypure hydroxyl group-containing vinyl ethers.

[0071] In accordance with the present invention, the starting materialalcohols in the transesterification reaction are compositions containinghydroxyl group-containing vinyl ethers. The above hydroxylgroup-containing vinyl ethers may be the compounds represented by theabove general formula (2), in which the substituent represented by R³ isa hydrogen atom or an organic residue and the substituent represented byR² is an organic residue.

[0072] The above R² and R³ are the same as the R² and R³ in the abovegeneral formula (1), respectively.

[0073] Typical examples of the hydroxyl group-containing vinyl ethersrepresented by the above general formula (2) specifically include thefollowing preferred ones: 2-Hydroxyethyl vinyl ether, 3-hydroxypropylvinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxycyclohexyl vinylether, 1,6-hexanediol monovinyl ether, 1,4-cyclohexanedimethanolmonovinyl ether, diethylene glycolmonovinyl ether, triethylene glycolmonovinyl ether and dipropylene glycol monovinyl ether.

[0074] The raw material compositions used in the practice of theinvention contain, in addition to the hydroxy-containing vinyl ethersrepresented by the above general formula (2), at least one compoundselected from the group consisting of divinyl ethers represented by theabove general formula (4), 2-substituted-1,3-dioxo compounds representedby the above general formula (5) and unsaturated bond-containing vinylethers represented by the above general formula (6). The divinyl ethersof the above general formula (4), 2-substituted-1,3-dioxo compound ofthe above general formula (5) and unsaturated bond-containing vinylethers of the above general formula (6) may be contained respectivelysingly or two or more of them may be contained.

[0075] The lower limit to the total amount of the impurities representedby the above general formulas (4), (5) and (6) is preferably not lessthan 0.01% by weight, more preferably not less than 0.05% by weight,still more preferably not less than 0.1% by weight, particularlypreferably not less than 0.5% by weight, but preferably not more than70% by weight, more preferably not more than 50% by weight, still morepreferably not more than 30% by weight, particularly preferably not morethan 20% by weight, relative to the raw material composition. The aboveimpurity content range is preferred from the viewpoint of reaction rate,yield and economy.

[0076] The impurities represented by the above general formula (4), theabove general formula (5) and the above general formula (6) arepreferably contained in the starting material hydroxyl group-containingvinyl ethers of the above general formula (2). They may also occur inthe reaction system, however, as a result of intentional addition to thereaction system or formation during the reaction, for instance.

[0077] In cases where the above impurities occur in the reaction system,the lower limit to the total amount thereof is preferably not less than0.001% by weight, more preferably not less than 0.005% by weight,particularly preferably not less than 0.01% by weight, but preferablynot more than 10% by weight, more preferably not more than 8% by weight,still more preferably not more than 5% by weight, particularlypreferably not more than 3% by weight, relative to the reaction system.The above impurity content range is preferred from the viewpoint ofreaction rate, yield and economy.

[0078] One species of the impurities to be contained in the hydroxylgroup-containing vinyl ethers in the practice of the present inventionis the divinyl ethers. The divinyl ethers may be those compoundsrepresented by the above general formula (4), in which the substituentrepresented by R³ may be the same or different and each is a hydrogenatom or an organic residue and the substituent represented by R² is anorganic residue.

[0079] The above R² and R³ are the same as mentioned above.

[0080] Typical examples of the divinyl ethers represented by the abovegeneral formula (4) specifically include such preferred ones as divinylether, ethylene glycol divinyl ether, propylene glycol divinyl ether,propanediol divinyl ether, butanediol divinyl ether, 1,4-cyclohexanedivinyl ether, 1,6-hexanediol divinyl ether, 1,4-cyclohexanedimethanoldivinyl ether, diethylene glycol divinyl ether, triethylene glycoldivinyl ether and dipropylene glycol divinyl ether.

[0081] One species of the impurities to be contained in the hydroxylgroup-containing vinyl ethers in accordance with the present inventionis the 2-substituted-1,3-dioxo compounds, and may be the compoundsrepresented by the general formula (5), in which the substituentrepresented by R³ is a hydrogen atom or an organic residue and thesubstituent represented by R² is an organic residue.

[0082] The above R² and R³ are the same as mentioned above.

[0083] Typical examples of the 2-substituted-1,3-dioxo compoundsrepresented by the above general formula (5) specifically include suchpreferred ones as 2-methyl-1,3-dioxolane, 2,4-dimethyl-1,3-dioxolane,2-methyl-1,3-dioxane, 2-methyl-1,3-dioxepane, 1,6-hexanediolacetaldehyde cyclic acetal, diethylene glycol acetaldehyde cyclicacetal, triethylene glycol acetaldehyde cyclic acetal and dipropyleneglycol acetaldehyde cyclic acetal.

[0084] One species of the impurities to be contained in the hydroxylgroup-containing vinyl ethers in accordance with the present inventionis the unsaturated bond-containing vinyl ethers, and may be thecompounds represented by the above general formula (6), in which thesubstituent represented by R³ is a hydrogen atom or an organic residueand the substituent represented by R⁵ is an organic residue containingan unsaturated bond represented by —CR⁶═CR⁷—.

[0085] The above R³ is the same as mentioned above.

[0086] The organic residue represented by R⁵ in the above generalformula (6) and containing an unsaturated bond represented by —CR⁶═CR⁷—,in which R⁶ and R⁷ are the same or different and each is a hydrogen atomor an organic residue, is an organic residue having a structure derivedfrom the —R²—OH group in the general formula (2) by dehydration.Specifically, when —R²—OH is —CH₂CH₂CH₂—OH, for instance, the organicresidue represented by R⁵ is —CH₂CH═CH₂ and both of R⁶ and R⁷ arehydrogen atoms. When —R²—OH is —CH₂CH(OH)CH₃, the organic residuerepresented by R⁵ is —CH₂CH═CH₂ or —CH═CH—CH₃ and R⁶ is a hydrogen atomin either case and R⁷ is a hydrogen atom or a methyl group.

[0087] Typical examples of the unsaturated bond-containing vinyl ethersrepresented by the above general formula (6) specifically include suchpreferred ones as2-propenyl vinyl ether, 1-propenyl vinyl ether,3-butenyl vinyl ether and 5-hexenyl vinyl ether.

[0088] The (meth)acrylic esters, which are starting materials in thepractice of the invention may be those compounds represented by theabove general formula (3), in which the substituent represented by R¹ isa hydrogen atom or a methyl group and the substituent represented by R⁴is an organic residue.

[0089] The organic residues represented by R⁴ in the above generalformula (3) are preferably, for example, straight, branched or cyclicalkyl groups containing 1 to 8 carbon atoms and aromatic groupscontaining 6 to 10 carbon atoms, which may optionally be substituted.Among these, alkyl groups containing 1 to 4 carbon atoms are preferablyused.

[0090] Typical examples of the (meth)acrylic esters represented by theabove general formula (3) are, specifically, as preferred ones, loweralkyl (meth)acrylic esters such as methyl (meth)acrylate, ethyl(meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl(meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate andtert-butyl (meth)acrylate. These may be used singly or in admixture.

[0091] In the practice of the invention, the transesterificationreactions are preferably carried out in the presence oftransesterification catalysts. The alcohols formed as reactionbyproducts are preferably removed from the reaction system.

[0092] As for the reaction mole ratio between the (meth)acrylic estersand the hydroxyl group-containing vinyl ethers in the abovetransesterification reactions, specifically, the (meth)acrylicesters/hydroxyl group-containing vinyl ethers mole ratio is preferablywithin the range of 6/1 to 1/5, more preferably within the range of 5/1to 1/3, still more preferably within the range of 4/1 to 1/2,particularly preferably within the range of 3/1 to 1/1. The above moleratio range is preferred from the viewpoint of yield and economy.

[0093] The above transesterification catalysts are, specifically, aspreferred ones, oxides such as calcium oxide, barium oxide, lead oxide,zinc oxide and zirconium oxide; hydroxides such as potassium hydroxide,sodium hydroxide, lithium hydroxide, calcium hydroxide, thalliumhydroxide, tin hydroxide, lead hydroxide and nickel hydroxide; halidessuch as lithium chloride, calcium chloride, tin chloride, lead chloride,zirconium chloride and nickel chloride; carbonate salts such aspotassium carbonate, rubidium carbonate, cesium carbonate, leadcarbonate, zinc carbonate and nickel carbonate; hydrogen carbonate saltssuch as potassium hydrogen carbonate, rubidium hydrogen carbonate andcesium hydrogen carbonate; phosphate salts such as sodium phosphate,potassium phosphate, rubidium phosphate, lead phosphate, zinc phosphateand nickel phosphate; nitrate salts such as lithium nitrate, calciumnitrate, lead nitrate, zinc nitrate and nickel nitrate; carboxylatesalts such as lithium acetate, calcium acetate, lead acetate, zincacetate and nickel acetate; alkoxy compounds such as sodium methoxide,sodium ethoxide, potassium methoxide, potassium ethoxide, potassiumtert-butoxide, calcium methoxide, calcium ethoxide, barium methoxide,barium ethoxide, tetraethoxytitanium, tetrabutoxytitanium andtetra(2-ethylhexanoxy)titanium; acetylacetonato complexes such aslithium acetylacetonate, zirconia acetylacetonate, zinc acetylacetonate,dibutoxytin acetylacetonate and dibutoxytitanium acetylacetonate;quaternary ammonium alkoxides such as tetramethylammonium methoxide,tetramethylammonium tert-butoxide and trimethylbenzylammonium ethoxide;dialkyltin compounds such as dimethyltin oxide, methylbutyltin oxide,dibutyltin oxide and dioctyltin oxide; distannoxanes such asbis(dibutyltin acetate) oxide and bis(dibutyltin laurate) oxide; anddialkyltin dicarboxylate salts such as dibutyltin diacetate anddibutyltin dilaurate. These may be used singly or two or more of themmay be used in combination.

[0094] Among these transesterification catalysts, potassium carbonate,cesium carbonate, tetraethoxytitanium, tetrabutoxytitanium,tetra(2-ethylhexanoxy)titanium, zirconia acetylacetonate, dibutyltinoxide, dioctyltin oxide, bis (dibutyltin acetate) oxide, bis (dibutyltinlaurate) oxide, dibutyltin diacetate and dibutyltin dilaurate arepreferably used.

[0095] The level of addition of the above transesterification catalystsis, specifically, preferably not less than 0.001 mole percent, morepreferably not less than 0.005 mole percent, still more preferably notless than 0.01 mole percent, particularly preferably not less than 0.05mole percent, but preferably not more than 20 mole percent, morepreferably not more than 15 mole percent, still more preferably not morethan 10 mole percent, particularly preferably not more than 5 molepercent. The above range of transesterification catalyst addition levelis preferred from the viewpoint of yield and economy.

[0096] As the method of removing the above by product alcohols, forexample, the method comprising carrying out the reaction under reducedpressure, the method comprising carrying out the reaction usingazeotropic solvents and the method comprising carrying out the reactionin the presence of adsorbents are preferred. Among these, the methodcomprising carrying out the reaction under reduced pressure and themethod comprising carrying out the reaction using azeotropic solventsare preferred.

[0097] The above azeotropic solvents may be ones which do not adverselyaffect the reaction. Specifically, ethers such as diethyl ether,diisopropyl ether and dibutyl ether; aromatic hydrocarbons such asbenzene, toluene and xylene; aliphatic hydrocarbons such as pentane,hexane, heptane and cyclohexane; halogenated hydrocarbons such aschloroform, methylene chloride, 1,2-dichloroethane and chlorobenzene;and the like are preferred. These azeotropic solvents may be used singlyor two or more of them may be used in combination.

[0098] The level of addition of the above azeotropic solvents is,specifically, preferably not less than 0% by weight relative to thetotal weight of the (meth)acrylic esters represented by the generalformula (3) and the hydroxyl group-containing vinyl ethers representedby the general formula (2). Conversely, it is preferably not more than300% by weight, more preferably not more than 200% by weight, still morepreferably not more than 150% by weight, particularly preferably notmore than 100% by weight, relative to the total weight of the(meth)acrylic esters represented by the general formula (3) and thehydroxyl group-containing vinyl ethers represented by the generalformula (2). The above range of the organic solvent addition level ispreferred from the viewpoint of yield and economy.

[0099] The (meth)acrylic ester used in excess as well as the impuritiesrepresented by the above general formulas (4), (5) and (6) may alsoserve as the azeotropic solvent.

[0100] The reaction temperature for the above reaction is preferably notlower than the boiling point or azeotropic point of the by productalcohol. Specifically, the temperature is preferably not lower than 40°C., more preferably not lower than 50° C., particularly preferably notlower than 60° C. Conversely, it is preferably not higher than180° C.,more preferably not higher than 170° C., particularly preferably nothigher than 160° C. The reaction pressure may be at ordinary pressure,under pressure or under reduced pressure. The reaction time canappropriately be selected so that the above reaction can be driven tocompletion.

[0101] From the viewpoint of polymerization inhibition and yield, theproduction of the vinyl ether group-containing (meth)acrylic esters ofthe above general formula (1) is preferably carried out in the presenceof polymerization inhibitors. As for the polymerization inhibitors,those radical polymerization inhibitors mentioned above are preferablyused, for instance, and one or two or more of them may be used.

[0102] The level of addition of the above polymerization inhibitors mayvary according to the species of the (meth)acrylic ester of the generalformula (3) as used and the species of the product vinyl ethergroup-containing (meth)acrylic ester of the general formula (1) but ispreferably within the range of not less than 0.0001% by weight, morepreferably not less than 0.0002% by weight, still more preferably notless than 0.0005% by weight, particularly preferably not less than0.001% by weight, but preferably not more than 5% by weight, morepreferably not more than 1% by weight, still more preferably not morethan 0.5% by weight, particularly preferably not more than 0.1% byweight relative to the (meth)acrylic esters of the general formula (3).The above range of polymerization inhibitor addition level is preferredfrom the viewpoint of yield, polymerization inhibition and economy.

[0103] In the production method according to the invention, it is alsopreferable to cause basic compounds to coexist with radicalpolymerization inhibitors. Suited for use as basic compounds are thesame ones as mentioned hereinabove, and one or two or more of them maybe used.

[0104] The level of addition of the above basic compounds may varyaccording to the species of the starting material hydroxylgroup-containing vinyl ether and the species of the product vinyl ethergroup-containing (meth)acrylic ester of the general formula (1) butpreferably is not less than 0.0001% by weight, more preferably not lessthan 0.0002% by weight, still more preferably not less than 0.0005% byweight, particularly preferably not less than 0.001% by weight, butpreferably not more5% by weight, more preferably not more 1% by weight,still more preferably not more than 0.5% by weight, particularlypreferably not more than 0.1% by weight, relative to the above hydroxylgroup-containing vinyl ethers. The above range of basic compound ispreferred from the viewpoint of yield, polymerization inhibition andeconomy.

[0105] As the method of producing vinyl ether group-containing(meth)acrylic esters according to the present invention, the method ofproducing a vinyl ether group-containing (meth)acrylic ester whichcomprises reacting a hydroxyl group-containing vinyl ether representedby the above general formula (2) with a (meth)acrylic ester representedby the above general formula (3) in the presence of not more than 5% byweight of water (production method (b)), the method of producing a vinylether group-containing (meth)acrylic ester which comprises reacting ahydroxyl group-containing vinyl ether represented by the above generalformula (2) with a (meth)acrylic ester represented by the above generalformula (3) in an atmosphere such that a molecular oxygen concentrationis 0.01 to 10% by volume (production method (c)), the method ofproducing a vinyl ether group-containing (meth)acrylic ester which iscarried out in a lightproof structure (production method (d)) and themethod of producing a vinyl ether group-containing (meth)acrylic esterwhich is carried out in a lightproof structure in an atmosphere suchthat a molecular oxygen concentration in the gaseous phase within saidlightproof structure is 0.01 to 15% by volume (production method (e))are preferred.

[0106] Also suited are the method of producing a vinyl ethergroup-containing (meth)acrylic ester which comprises reacting a hydroxylgroup-containing vinyl ether represented by the above general formula(2) with a (meth)acrylic ester represented by the general formula (3) inthe presence of an N-nitrosophenylhydroxylamine salt represented by thefollowing general formula (7):

[0107] in the formula, M represents a metal atom or an ammonium groupand n represents an integer equal to the valence of M (production method(f)) and the method of producing a vinyl ether group-containing(meth)acrylic ester which comprises reacting a hydroxyl group-containingvinyl ether represented by the above general formula (2) with a(meth)acrylic ester represented by the above general formula (3) in anatmosphere such that a molecular nitrogen monoxide (NO) and/or molecularnitrogen dioxide (NO₂) concentration in the gaseous phase in thereaction system is 0.01 to 10% by volume (production method (g)). One ofthese production methods may be carried out or the production methodsmentioned above may be carried out in appropriate combination. It ispreferred, however, that they be carried out in appropriate combination.

[0108] In the above production methods (b), (c), (f) and (g), hydroxylgroup-containing vinyl ethers of the above general formula (2) and(meth)acrylic esters of the above general formula (3) are subjected totransesterification reaction. The hydroxyl group-containing vinyl ethersof the above general formula (2), the (meth)acrylic esters of the abovegeneral formula (3), the methods of subjecting these totransesterification reaction and the reactions conditions, and the like,are the same as those mentioned hereinabove. Further, in carrying outthe transesterification reaction, the reaction is preferably carried outin the presence of the above-mentioned radical polymerization inhibitorsor the radical polymerization inhibitors and the basic compounds. Thelevels of addition of the radical polymerization inhibitors and basiccompounds are the same as in the production method (a).

[0109] The above production method (b) is carried out in the presence ofnot more than 5% by weight of water. Thus, the amount of water in theliquid phase in the reaction system is kept at not more than 5% byweight relative to the total weight of the liquid phase in the reactionsystem. In the above production method (b), the amount of water in thereaction system, namely in the liquid phase in the reaction system, isnot more than 5% by weight, preferably not more than 3% by weight, morepreferably not more than 1% by weight, relative to the total weight ofthe liquid phase in the reaction system. The above water content rangeis preferred from the viewpoint of selectivity, yield and economy.

[0110] In the above production method (c), the transesterificationreaction is carried out in an atmosphere such that the molecular oxygenconcentration in the gaseous phase in the reaction system is 0.01 to 10%by volume. By selecting the molecular oxygen concentration in thegaseous phase in the reaction system in the above range, thepolymerization in the above reaction system can be effectively inhibitedand the desired vinyl ether group-containing (meth)acrylic ester can beproduced in high yields. In a preferred embodiment, the molecular oxygenconcentration in the gaseous phase in the above reaction system is notless than 0.02% by volume, more preferably not less than 0.05% byvolume, but preferably not more than 9% by volume, more preferably notmore than 8% by volume. The above molecular oxygen concentration rangeis preferred from the viewpoint of yield, polymerization inhibition inreaction system, explosion avoidance and economy.

[0111] Available for adjusting the molecular oxygen concentration in theabove gaseous phase to 0.01 to 10% by volume are (a) the methodcomprising feeding molecular oxygen or a molecular oxygen-containinggas, such as air, into a reaction vessel (vapors occurring therein)during reaction until that concentration falls within the range of 0.01to 10% by volume relative to the volume of the gaseous phase in thereaction system, (b) the method comprising feeding molecular oxygen or amolecular oxygen-containing gas, such as air, and an inert gas, such asnitrogen or argon, respectively into a reaction vessel (vapors occurringtherein) during reaction until the concentration falls within the rangeof 0.01 to 10% by volume relative to the volume of the gaseous phase inthe reaction system, (c) the method comprising admixing molecular oxygenor a molecular oxygen-containing gas, such as air, with an inert gas,such as nitrogen or argon, in advance and feeding the mixture into areaction vessel (vapors occurring therein) during reaction until theconcentration falls within the range of 0.01 to 10% by volume relativeto the volume of the gaseous phase in the reaction system, and the like.

[0112] As the methods for feeding molecular oxygen or a mixed gascontaining molecular oxygen to the reaction system, it may be fed to oneor both of the liquid phase and gaseous phase in the reaction systemeither continuously or intermittently.

[0113] In the above production method (f), the polymerization in theabove reaction system can be effectively inhibited and the desired vinylether group-containing (meth)acrylic esters can be produced in highyield by causing N-nitrosophenyl-hydroxylamine salts represented by theabove general formula (7) to coexist in the step of thetransesterification reaction. The N-nitrosophenylhydroxylamine salts ofthe general formula (7) may be used singly or two or more species may beused in combination.

[0114] Referring to the above general formula (7), typical examples ofthe metal atom represented by M are aluminum, copper, iron(III), tin,zinc, magnesium and the like. Among these, aluminum is particularlypreferred.

[0115] The level of addition of the above N-nitrosophenyl-hydroxylaminesalts is preferably not less than 0.00001% by weight, more preferablynot less than 0.0001% by weight, still more preferably not less than0.0002% by weight, particularly preferably not less than 0.0005% byweight, but preferably not more5% by weight, more preferably not morel%by weight, still more preferably not more than 0.5% by weight,particularly preferably not more than 0.1% by weight, relative to the(meth)acrylic esters represented by the above general formula (3). Theabove range of N-nitrosophenylhydroxylamine salt addition level ispreferred from the viewpoint of yield, polymerization inhibition inreaction system, and economy.

[0116] In the above production method (g), the polymerization in theabove reaction system can be effectively inhibited and the desired vinylether group-containing (meth)acrylic esters can be produced in highyields by carrying out the transesterification reaction in an atmospheresuch that the molecular nitrogen monoxide (NO) and/or molecular nitrogendioxide (NO₂) concentration in the gaseous phase in the reaction systemis 0.01 to 10% by volume.

[0117] The molecular nitrogen monoxide (NO) and/or molecular nitrogendioxide (NO₂) concentration in the gaseous phase in the above reactionsystem is preferably not less than 0.01% by volume, more preferably notless than 0.02% by volume, still more preferably not less than 0.05% byvolume, but preferably not more than 10% by volume, more preferably notmore than 9% by volume, still more preferably not more than 8% byvolume. The above range of molecular nitrogen monoxide (NO) and/ormolecularnitrogendioxide (NO₂) concentration is preferred from theviewpoint of yield, polymerization inhibition in reaction system,explosion avoidance, and economy.

[0118] For adjusting the molecular nitrogen monoxide (NO) and/ormolecular nitrogen dioxide (NO₂) concentration in the above gaseousphase to 0.01 to 10% by volume, there are available, (a) the methodcomprising feeding a gas containing molecular nitrogen monoxide (NO)and/or molecular nitrogen dioxide (NO₂) into a reaction vessel (vaporsoccurring therein) during reaction until the concentration falls within0.01 to 10% by volume relative to the volume of the gaseous phase in thereaction system, (b) the method comprising feeding molecular nitrogenmonoxide (NO) and/or molecular nitrogen dioxide (NO₂) and an inert gas,such as nitrogen or argon, respectively into a reaction vessel (vaporsoccurring therein) during reaction until the concentration falls within0.01 to 10% by volume relative to the volume of the gaseous phase in thereaction system, and (c) the method comprising admixing molecularnitrogen monoxide (NO) and/or molecular nitrogen dioxide (NO₂) with aninert gas, such as nitrogen or argon, in advance and feeding the mixtureinto a reaction vessel (vapors occurring therein) during reaction untilthe concentration falls within 0.01 to 10% by volume relative to thevolume of the gaseous phase in the reaction system.

[0119] As the method for feeding molecular nitrogen monoxide (NO) and/ormolecular nitrogen dioxide (NO₂), or a mixed gas containing molecularnitrogen monoxide (NO) and/or molecular nitrogen dioxide (NO₂) to thereaction system, it may be fed to one or both of the liquid phase andgaseous phase in the reaction system either continuously orintermittently.

[0120] The term “production” as used herein referring to the aboveproduction methods (d) and (e) includes, within the meaning thereof, thesteps of raw materials charging, reaction, reaction solution transferand so forth. These steps may be carried out independently or two ormore of them may be carried in appropriate combination. Among these, theraw materials charging step and the reaction step, in particular, aremeant by the term.

[0121] The above production methods (d) and (e) can be applied, forexample, in carrying out the above-mentioned production methods A to F.Among these, the production method which comprises subjecting(meth)acrylic esters and hydroxyl group-containing vinyl ethers totransesterification reaction (production method D) is preferred from theindustrial viewpoint. As the hydroxyl group-containing vinyl ethers and(meth)acrylic esters, the same ones as those hydroxyl group-containingvinyl ethers represented by the general formula (2) and those(meth)acrylic esters represented by the general formula (3), and thelike are preferred. The method of subjecting these totransesterification reaction and the reaction conditions may be the sameas mentioned referring to the production methods mentioned above, forinstance.

[0122] In cases where the mode of the above production methods (d) and(e) are applied to the production methods A to F, it is preferred ineach case that radical polymerization inhibitors and/or basic compoundsbe caused to coexist. Furthermore, in carrying out thetransesterification reaction, the reaction is preferably carried out inthe presence of the above-mentioned radical polymerization inhibitors orthe radical polymerization inhibitors and the basic compounds.

[0123] The level of addition of the radical polymerization inhibitorsmay vary according to the species of the starting material (meth)acryliccompound, such as (meth)acrylic acid, (meth)acrylic halide,(meth)acrylic anhydride, (meth)acrylic ester, (meth)acrylic acid alkali(or alkaline earth) metal salt or the like, and the level of addition ofthe above basic compounds may vary according to the species of thestarting material vinyl ether, such as hydroxyl group-containing vinylether, halogen-containing vinyl ether or the like. However, they are thesame as in the production method (a).

[0124] According to the above production method (d), vinyl ethergroup-containing (meth)acrylic esters represented by the above generalformula (1) can be produced in a stable manner by producing them inlightproof structures. As the lightproof structures used in production,there may be mentioned structures made of lightproof materials such asreaction vessels, reaction apparatus, mixing apparatus, tanks, pipes,nozzles, valves and the like for the production purpose. The insidesurface area of the structures to which light can reach is the same asmentioned above. The lightproof materials are also preferably the sameones as mentioned above. According to the above production method (e),vinyl ether group-containing (meth)acrylic esters represented by theabove general formula (1) can be produced in a more stable manner byproducing them in lightproof structures in an atmosphere such that themolecular oxygen concentration in the gaseous phase within saidlightproof structures is 0.01 to 15% by volume.

[0125] In this manner, by carrying out the reaction while adjusting themolecular oxygen concentration in the gaseous phase within thelightproof structures to 0.01 to 15% by volume, it becomes possible toeffectively inhibit the polymerization of vinyl ether group-containing(meth)acrylic esters in the liquid phase and/or gaseous phase as well asthe formation of impurities and of peroxides, hence it becomes possibleto produce the desired vinyl ether group-containing (meth)acrylic estersin high yields.

[0126] The molecular oxygen concentration in the gaseous phase withinthe above lightproof structures is generally 0.01 to 15% by volume.Preferably, however, it is not less than 0.02% by volume, particularlypreferably not less than 0.05% by volume, but preferably not more than12% by volume, particularly preferably not more than 10% by volume. Ifthe molecular oxygen concentration within the gaseous phase in thelightproof structures is less than 0.01% by volume, the startingmaterial (meth)acrylic compounds and the vinyl ether group-containing(meth)acrylic esters may undergo polymerization due to free of oxygen.If the molecular oxygen concentration in the gaseous phase within thestructures is higher than 15% by volume, the formation of impurities andof peroxides and the polymerization of the vinyl ether group-containing(meth)acrylic esters may occur. Therefore, the above molecular oxygenconcentration range is preferred from the viewpoint of yield,polymerization inhibition, and economy.

[0127] The above-mentioned formation of impurities and of peroxides andpolymerization of vinyl ether group-containing (meth)acrylic esters aremore accelerated in structures permeable to light and, therefore, it isnecessary to carry out the production inside lightproof structures.

[0128] In adjusting the molecular oxygen concentration in the gaseousphase within the lightproof structures to 0.01 to 15% by volume, thosemethods of adjusting the molecular oxygen concentration mentionedhereinabove can be applied. As for the gas feeding method, the gas maybe fed to one or both of the liquid phase and gaseous phase eithercontinuously or intermittently in each step of the production process.

[0129] The vinyl ether group-containing (meth)acrylic esters of thegeneral formula (1) produced by the above production methods can beobtained by purifying the reaction solution.

[0130] As methods of purifying the vinyl ether group-containing(meth)acrylic esters represented by the above general formula (1), theremay preferably be applied, for example, the method of purifying a vinylether group-containing (meth)acrylic ester which is carried out in anatmosphere such that the molecular oxygen concentration in the gaseousphase in the purification system is 0.01 to 10% by volume (purificationmethod (a)), the method of purifying vinyl ether group-containing(meth)acrylic esters which is carried out in a lightproof structure inan atmosphere such that the molecular oxygen concentration in thegaseous phase in the purification system is 0.01 to 15% by volume(purification method (b)) and a combination of these. Theabove-mentioned purification method (a) and purification method (b)constitute a further aspect of the present invention.

[0131] The methods of purifying vinyl ether group-containing(meth)acrylic esters according to the invention are described below.

[0132] The above term “purification” used herein means procedures afterwhich the vinyl ether group-containing (meth)acrylic esters representedby the general formula (1) have improved concentration and/or purity ascompared with the value before that procedure. More specifically,procedures include raw materials recovery, catalysts recovery,neutralization, filtration, decantation, extraction, water washing,evaporation, distillation, column chromatography and other procedures.The above procedures may be performed singly or two or more may beperformed in appropriate combination. Among them, the distillationprocedure is particularly preferred.

[0133] As the “lightproof structures” used in the above purification,there may be mentioned structures made of lightproof materials such asdistillation vessels, distillation towers, rectification towers,distillation apparatus, separation apparatus, filtration apparatus,mixing apparatus, tanks, pipes, nozzles, valves and the like, for thepurification purpose. The inside surface area of the structures to whichlight can reach is the same as mentioned above. The lightproof materialsare also preferably the same ones as mentioned above.

[0134] In the above purification method (a), the impurity formation dueto polymerization and decomposition in the above process of purificationcan be effectively prevented and the desired vinyl ethergroup-containing (meth)acrylic esters can be purified stably in simpleand economical manners by carrying out the purification procedure in anatmosphere such that the molecular oxygen concentration in the gaseousphase in the purification system is 0.01 to 10% by volume.

[0135] The molecular oxygen concentration in the gaseous phase in theabove purification system is 0.01 to 10% by volume. Preferably, however,it is not less than 0.02% by volume, particularly preferably not lessthan 0.05% by volume, but preferably not more than 9% by volume,particularly preferably not more than 8% by volume. The above molecularoxygen concentration range is preferred from the viewpoint of yield,polymerization inhibition, impurity formation prevention and economy.

[0136] In adjusting the molecular oxygen concentration to 0.01 to 10% byvolume, the above-mentioned methods of adjusting the molecular oxygenconcentration can be applied. As for the methods of gas feeding to thepurification system, the gas may be fed to one or both of the liquidphase and gaseous phase in the purification system either continuouslyor intermittently.

[0137] In the above purification method (b), the impurity formation dueto polymerization and decomposition in the above process of purificationcan be effectively prevented and the desired vinyl ethergroup-containing (meth)acrylic esters can be purified stably in simpleand economical manners by carrying out the purification procedure inlightproof structures in an atmosphere such that the molecular oxygenconcentration in the gaseous phase in the purification system is 0.01 to15% by volume.

[0138] The molecular oxygen concentration in the gaseous phase in theabove purification system is 0.01 to 15% by volume. Preferably, however,it is not less than 0.02% by volume, particularly preferably not lessthan 0.05% by volume, but preferably not more than 12% by volume,particularly preferably not more than 10% by volume. The above molecularoxygen concentration range is preferred from the viewpoint of yield,polymerization inhibition, and economy.

[0139] In adjusting the molecular oxygen concentration in the gaseousphase in the above purification system to 0.01 to 15% by volume and ingas feeding, the same methods as in the purification method (a) can beapplied.

[0140] As the use of the vinyl ether group-containing (meth)acrylicester compositions according to the invention and of the vinyl ethergroup-containing (meth)acrylic esters produced and purified according tothe invention, they can be used in a wide range, for example as rawmaterials in the medicinal and agricultural chemicals, as syntheticintermediates and further as polymerizable materials.

[0141] The present invention, which has the constitution mentionedabove, can improve the stability of vinyl ether group-containing(meth)acrylic esters by preventing the polymerization of the vinyl ethergroup-containing (meth)acrylic esters during storage and handlingthereof without impairing the polymerizability thereof and thus makes itpossible to handle the vinyl ether group-containing (meth)acrylic estersin a stable manner. It further makes it possible to produce and purifyvinyl ether group-containing (meth)acrylic esters in a simple,economical and stable manner while preventing the formation ofimpurities due to polymerization and decomposition in the process ofproduction or purification of the vinyl ether group-containing(meth)acrylic esters.

EXAMPLES

[0142] The following examples illustrate the present invention infurther detail. They are, however, by no means limitative of the scopeof the invention.

Example 1

[0143] A vinyl ether group-containing (meth)acrylic ester compositionwas prepared by adding 10 mg of methoxyhydroquinone, a radicalpolymerization inhibitor, to 100 g of 2-vinyloxyethyl acrylate. Thecomposition was placed in a sealed container and stored at 50° C. for120 days. Thereafter, as results of analyses by visual observation andby an HLC-8120 GPC type gel permeation chromatography (product of Tosoh;hereinafter referred to as “GPC”) with tetrahydrofuran as the carrier,neither discoloration nor high-molecular compound formation wasobserved.

Examples 2 to 12

[0144] The same procedure as in Example 1 was followed except that thevinyl ether group-containing (meth)acrylic ester and/or radicalpolymerization inhibitor used differed in species and/or the amountsthereof were varied. The species used, the amounts thereof and theresults of visual observation and GPC are shown in Table 1. TABLE 1Example 1 2 3 4 5 6 7 Vinyl ether group-containing VEA VEA VEM VEM VEEAVEEA VEEM (meth) acrylic ester (g) 100 100 100 100 100 100 100 Radicalpolymerization inhibitor MEHQ PTZ HQ TEMPO MEHQ TEMPO MEHQ (mg) 10 10 1010 10 10 10 Storage temperature 50° C. 50° C. 50° C. 50° C. 50° C. 50°C. 50° C. Number of days of storage 120 days 120 days 120 days 120 days120 days 120 days 120 days Visual observation No change No change Nochange No change No change No change No change Result of GPC analysis NoNo No No No No No polymer polymer polymer polymer polymer polymerpolymer formed formed formed formed formed formed formed Example 8 9 1011 12 Vinyl ether group-containing VEEM VBA VBA VBM VBM (meth) acrylicester (g) 100 100 100 100 100 Radical polymerization inhibitor TEMPO PTZTEMPO MEHQ PTZ (mg) 10 10 10 10 10 Storage temperature 50° C. 50° C. 50°C. 50° C. 50° C. Number of days of storage 120 days 120 days 120 days120 days 120 days Visual observation No change No change No change Nochange No change Result of GPC analysis No No No No No polymer polymerpolymer polymer polymer formed formed formed formed formed

[0145] The symbols used in Table 1 are as follows.

[0146] As regards the vinyl ether group-containing (meth)acrylic esters,VEA stands for 2-vinyloxyethyl acrylate, VEM for2-vinyloxyethylmethacrylate, VEEA for 2-(vinyloxyethoxy) ethyl acrylate,VEEM for 2-(vinyloxyethoxy) ethyl methacrylate, VBA for 4-vinyloxybutylacrylate, and VBM for 4-vinyloxybutyl methacrylate. As regards theradical polymerization inhibitors, MEHQ stands for methoxyhydroquinone,PTZ for phenothiazine, HQ for hydroquinone, and TEMPO for2,2,6,6-tetramethylpiperidine-N-oxyl.

Example 13

[0147] A vinyl ether group-containing (meth)acrylic ester compositionwas prepared by adding 5 mg of methoxyhydroquinone, a radicalpolymerization inhibitor, and 5 mg of sodium hydroxide, a basiccompound, to 100 g of 2-vinyloxyethyl acrylate, and the composition wasplaced in a sealed container and stored at 50° C. for 120 days. Asresults of analyses by visual observation and GPC, neither discolorationnor high-molecular compound formation was observed.

Examples 14 to 24

[0148] The same procedure as in Example 13 was followed except that thevinyl ether group-containing (meth)acrylic ester and/or radicalpolymerization inhibitor and/or basic compound used differed in speciesand/or the amounts thereof were varied. The species used, the amountsthereof and the results of visual observation and GPC are shown in Table2. TABLE 2 Example 13 14 15 16 17 18 19 Vinyl ether group-containing VEAVEA VEM VEM VEEA VEEA VEEM (meth) acrylic ester (g) 100 100 100 100 100100 100 Radical polymerization inhibitor MEHQ MEHQ MEHQ MEHQ MEHQ MEHQMEHQ (mg) 5 5 5 5 5 5 5 Basic compound NaOH TEHA NaOH TEHA NaOH TEHANaOH (mg) 5 5 5 5 5 5 5 Storage temperature 50° C. 50° C. 50° C. 50° C.50° C. 50° C. 50° C. Number of days of storage 120 days 120 days 120days 120 days 120 days 120 days 120 days Visual observation No change Nochange No change No change No change No change No change Result of GPCanalysis No No No No No No No polymer polymer polymer polymer polymerpolymer polymer formed formed formed formed formed formed formed Example20 21 22 23 24 Vinyl ether group-containing VEEM VBA VBA VBM VBM (meth)acrylic ester (g) 100 100 100 100 100 Radical polymerization inhibitorMEHQ MEHQ MEHQ MEHQ MEHQ (mg) 5 5 5 5 5 Basic compound TEHA NaOH TEHANaOH TEHA (mg) 5 5 5 5 5 Storage temperature 50° C. 50° C. 50° C. 50° C.50° C. Number of days of storage 120 days 120 days 120 days 120 days 120days Visual observation No change No change No change No change Nochange Result of GPC analysis No No No No No polymer polymer polymerpolymer polymer formed formed formed formed formed

[0149] The symbols used in Table 2 are as follows.

[0150] As regards the basic compounds, NaOH stands for sodium hydroxideand TEHA for tris(2-ethylhexyl)amine. The other symbols are the same asin Table 1.

Comparative Examples 1 to 6

[0151] A 100-g portion of each of radical polymerization inhibitor-freevinyl ether group-containing (meth)acrylic ester was placed in a sealedcontainer and stored at 50° C. An hour later, all the vinyl ethergroup-containing (meth)acrylic esters used began to become turbid and,after 5 hours, became white solids insoluble in tetrahydrofuran. Thevinyl ether group-containing (meth)acrylic esters used were as shown inTable 3. The symbols used in Table 3 are the same as above. TABLE 3Comparative Example 1 2 3 4 5 6 Vinyl ether group-containing VEA VEMVEEA VEEM VBA VBM (meth) acrylic ester (g) 100 100 100 100 100 100Radical polymerization inhibitor — — — — — — (mg) Basic compound — — — —— — (mg) Storage temperature 50° C. 50° C. 50° C. 50° C. 50° C. 50° C.Storage time 5 hrs 5 hrs 5 hrs 5 hrs 5 hrs 5 hrs Result THF-insolubleTHF-insoluble THF-insoluble THF-insoluble THF-insoluble THF-insolublesolid formed solid formed solid formed solid formed solid formed solidformed

[0152] except that radical polymerization inhibitor-free butylmethacrylate was used in Comparative Example 7 and radicalpolymerization inhibitor-free 2-(methoxyethoxy)ethyl methacrylate inComparative Example 8. Butyl methacrylate and 2-(methoxyethoxy) ethylmethacrylate both showed no turbidity for 10 hours, without formation ofany substance insoluble in tetrahydrofuran.

Example 25

[0153] A vinyl ether group-containing (meth)acrylic ester compositionwas prepared by adding 10 mg of methoxyhydroquinone, a radicalpolymerization inhibitor, to 100 g of 2-(vinyloxyethoxy)ethyl acrylate,and the composition was placed in a sealed container and stored at 100°C. for 12 hours. Until 5 hours later, no solid matter was detected byvisual observation. After 12 hours, however, the composition became asolid insoluble in tetrahydrofuran.

Example 26

[0154] The same procedure as in Example 25 was followed except that2-(vinyloxyethoxy) ethyl methacrylate was used in lieu of2-(vinyloxyethoxy)ethyl acrylate. Until 5 hours later, no solid matterwas detected by visual observation. After 12 hours, however, thecomposition became a solid insoluble in tetrahydrofuran.

Comparative Examples 9 and 10

[0155] The same procedure as in Example 25 was followed except that2-(methoxyethoxy)ethyl acrylate was used in Comparative Example 9 and2-(methoxyethoxy)ethyl methacrylate in Comparative Example 10. With both2-(methoxyethoxy)ethyl acrylate and 2-(methoxyethoxy)ethyl methacrylate,no tetrahydrofuran-insoluble matter formation was observed.

Example 27

[0156] The same procedure as in Example 13 was followed except that 100g of toluene was added following the production of the compositionobtained by Example 13. As results of analyses by visual observation andGPC, neither discoloration nor high-molecular compound formation wasobserved.

Example 28

[0157] The same procedure as in Example 13 was followed except that 50 gof toluene was added following the production of the compositionobtained by Example 13. As results of analyses by visual observation andGPC, neither discoloration nor high-molecular compound formation wasobserved.

Example 29

[0158] The same procedure as in Example 13 was followed except that 25 gof toluene was added following the production of the compositionobtained by Example 13. As results of analyses by visual observation andGPC, neither discoloration nor high-molecular compound formation wasobserved.

Example 30

[0159] The same procedure as in Example 13 was followed except that 10 gof toluene was added following the production of the compositionobtained by Example 13. As results of analyses by visual observation andGPC, neither discoloration nor high-molecular compound formation wasobserved.

Example 31

[0160] The same procedure as in Example 13 was followed except that 5 gof toluene was added following the production of the compositionobtained by Example 13. As results of analyses by visual observation andGPC, neither discoloration nor high-molecular compound formation wasobserved.

[0161] Each vinyl ether group-containing (meth)acrylic ester used in thefollowing Examples 32 to 55 was synthesized by the above-mentionedproduction method D and then purified by distillation under reducedpressure.

Example 32

[0162] A 100-g portion of 2-vinyloxyethyl acrylate having a watercontent of 0.01% by weight as determined by using a model MKS 510 KarlFischer moisture meter (product of Kyoto Denshi Kogyo, hereinafterreferred to as “moisture meter”; indicator: Hydranal Composite 5K(product of R&H Laborchemikalien GmbH & Co. KG); solvent: DehydratedSolvent KT (product of Mitsubishi Chemical)) was added to a test tubeand 10 mg of methoxyhydroquinone was further added. After mixing, a 21%(by volume) oxygen gas (the balance being nitrogen) was passed throughthe gaseous phase in the test tube for 10 minutes and then the test tubewas tightly stoppered.

[0163] The test tube prepared in the above manner was shaken on an oilbath maintained at 80° C. for 40 days, followed by visual observationand by analysis using a model GC-1700 gas chromatograph (product ofShimadzu; hereinafter this chromatographic analysis is referred to as“GC”), GPC and analysis using a model RQ Flex peroxide assayinginstrument (product of Merck Co. Ltd.; hereinafter this analysis isreferred to as “RQ assay”). While neither impurity formation norhigh-molecular substance formation was observed, a peroxide content of 2ppm was detected.

Examples 33 to 55

[0164] The same procedure as in Example 32 was repeated except that thevinyl ether group-containing (meth)acrylic ester and/or radicalpolymerization inhibitor used differed in species and/or the amountsthereof were varied and that the oxygen concentration and/or watercontent was varied and further that a basic compound was used or notused. The species used, the amounts thereof, the storage temperature,the number of days of storage, and the results of visual observation,GC, GPC and RQ assay are shown in Tables 4 to 6. The symbols used inTables 4 to 6 are the same as in Table 1 and Table 2. TABLE 4 Example 3233 34 35 36 37 38 39 Vinyl ether group-containing VEA VEM VEEA VEEA VEEMVEEM VBA VBM (meth) acrylic ester (g) 100 100 100 100 100 100 100 100Radical polymerization inhibitor MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ(mg) 10 10 10 5 10 5 10 10 Basic compound — — — TEHA — TEHA — — (mg) — —— 5 — 5 — — Oxygen concentration 21 vol % 21 vol % 21 vol % 21 vol % 21vol % 21 vol % 21 vol % 21 vol % Water content 0.01 wt % 0.05 wt % 0.01wt % 3 wt % 0.8 wt % 5 wt % 0.1 wt % 1 wt % Storage temperature 80° C.80° C. 80° C. 80° C. 80° C. 80° C. 80° C. 80° C. Number of days ofstorage 40 days 40 days 40 days 40 days 40 days 40 days 40 days 40 daysVisual observation No change No change No change No change No change Nochange No change No change Result of GC analysis 1% purity 1% purity 1%purity 3% purity 2% purity 3% purity 2% purity 2% purity decreasedecrease decrease decrease decrease decrease decrease decrease Result ofGPC analysis No polymer No polymer No polymer No polymer No polymer Nopolymer No polymer No polymer formed formed formed formed formed formedformed formed Result of RQ assay 2 ppm 2 ppm 2 ppm 2 ppm 2 ppm 2 ppm 2ppm 2 ppm

[0165] TABLE 5 Example 40 41 42 43 44 45 46 47 Vinyl ethergroup-containing VEA VEM VEEA VEEA VEEM VEEM VBA VBM (meth) acrylicester (g) 100 100 100 100 100 100 100 100 Radical polymerizationinhibitor MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ (mg) 10 10 10 5 10 510 10 Basic compound — — — TEHA — TEHA — — (mg) — — — 5 — 5 — — Oxygenconcentration 1.5 vol % 0.8 vol % 5 vol % 10 vol % 7 vol % 9 vol % 7 vol% 0.5 vol % Water content 7 wt % 7 wt % 7 wt % 7 wt % 7 wt % 7 wt % 7 wt% 7 wt % Storage temperature 80° C. 80° C. 80° C. 80° C. 80° C. 80° C.80° C. 80° C. Number of days of storage 40 days 40 days 40 days 40 days40 days 40 days 40 days 40 days Visual observation No change No changeNo change No change No change No change No change No change Result of GCanalysis 3% purity 3% purity 3% purity 3% purity 3% purity 3% purity 3%purity 3% purity decrease decrease decrease decrease decrease decreasedecrease decrease Result of GPC analysis No polymer No polymer Nopolymer No polymer No polymer No polymer No polymer No polymer formedformed formed formed formed formed formed formed Result of RQ assay Notdetected Not detected Not detected Not detected Not detected Notdetected Not detected Not detected

[0166] TABLE 6 Example 48 49 50 51 52 53 54 55 Vinyl ethergroup-containing VEA VEM VEEA VEEA VEEM VEEM VBA VBM (meth) acrylicester (g) 100 100 100 100 100 100 100 100 Radical polymerizationinhibitor MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ (mg) 10 10 10 5 10 510 10 Basic compound — — — TEHA — TEHA — — (mg) — — — 5 — 5 — — Oxygenconcentration 7 vol % 7 vol % 7 vol % 7 vol % 7 vol % 7 vol % 7 vol % 7vol % Water content 0.01 wt % 0.01 wt % 0.01 wt % 0.01 wt % 0.01 wt %0.01 wt % 0.01 wt % 0.01 wt % Storage temperature 80° C. 80° C. 80° C.80° C. 80° C. 80° C. 80° C. 80° C. Number of days of storage 40 days 40days 40 days 40 days 40 days 40 days 40 days 40 days Visual observationNo change No change No change No change No change No change No change Nochange Result of GC analysis No change No change No change No change Nochange No change No change No change Result of GPC analysis No polymerNo polymer No polymer No polymer No polymer No polymer No polymer Nopolymer formed formed formed formed formed formed formed formed Resultof RQ assay Not detected Not detected Not detected Not detected Notdetected Not detected Not detected Not detected

Example 56

[0167] 2-Vinyloxyethyl acrylate (100 g), 5 mg of methoxyhydroquinone and5 mg of tris (2-ethylhexyl) amine were added to a 200-mL SUS316container used as a lightproof structure. After mixing up, thegaseous phase in the container was completely substituted with a 7% (byvolume) oxygen gas (the balance being nitrogen), followed by tightclosure. The container was stored outdoors in an applicants' researchlaboratory at Suita, Osaka, Japan for 180 days starting from Apr. 1,2000, followed by visual observation, GC, GPC and RQ assay. Nodeterioration in quality was observed, namely neither impurityformation, nor high molecular substance formation nor peroxide formationwas detected.

Examples 57 to 74

[0168] The same procedure as in Example 56 was repeated except that thevinyl ether group-containing (meth)acrylic ester and/or radicalpolymerization inhibitor and/or basic compound used differed in speciesand/or the amounts thereof were varied and the oxygen concentration wasvaried. The species used, the amounts thereof and the results of visualobservation, GC, GPC and RQ assay are shown in Table 7 and Table 8. Thesymbols used in Tables 7 and 8 are the same as in Tables 1 and 2. TABLE7 Example 56 57 58 59 60 61 62 63 64 Vinyl ether VEA VEA VEA VEM VEM VEMVEEA VEEA VEEA group-containing (meth) acrylic ester (g) 100 100 100 100100 100 100 100 100 Radical MEHQ MEHQ PTZ MEHQ PTZ MEHQ MEHQ MEHQ PTZpolymerization inhibitor (mg) 5 10 10 5 10 10 5 10 10 Basic compoundTEHA — — TEHA — — TEHA — — (mg) 5 — — 5 — — 5 — — Oxygen 7 vol % 1 vol %21 vol % 0.8 vol % 10 vol % 21 vol % 5 vol % 0.1 vol % 21 vol %concentration Number of 180 days 180 days 180 days 180 days 180 days 180days 180 days 180 days 180 days days of storage Visual No change Nochange No change No change No change No change No change No change Nochange observation Result of No change No change No change No change Nochange No change No change No change No change GC analysis Result of Nopolymer No polymer No polymer No polymer No polymer No polymer Nopolymer No polymer No polymer GPC analysis formed formed formed formedformed formed formed formed formed Result of Not detected Not detectedNot detected Not detected Not detected Not detected Not detected Notdetected Not detected RQ assay

[0169] TABLE 8 Example 65 66 67 68 69 70 Vinyl VEEM VEEM VEEM VEEM VBAVBA ether group- containing (meth) acrylic ester (g) 100 100 100 100 100100 Radical MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ polymerization inhibitor (mg)5 10 10 10 5 10 Basic TEHA — — — TEHA — compound (mg) 5 — — — 5 — Oxygen0.5 vol % 9 vol % 21 vol % 30 vol % 15 vol % 0.2 vol % concentrationNumber 180 days 180 days 180 days 180 days 180 days 180 days of days ofstorage Visual No change No change No change No change No change Nochange observation Result No change No change No change No change Nochange No change of GC analysis Result No polymer No polymer No polymerNo polymer No polymer No polymer of GPC formed formed formed formedformed formed analysis Result Not detected Not detected Not detected 10ppm Not detected Not detected of RQ assay Example 71 72 73 74 Vinyl VBAVBM VBM VBM ether group- containing (meth) acrylic ester (g) 100 100 100100 Radical MEHQ MEHQ MEHQ MEHQ polymerization inhibitor (mg) 10 5 10 10Basic — TEHA — — compound (mg) — 5 — — Oxygen 21 vol % 18 vol % 0.3 vol% 21 vol % concentration Number 180 days 180 days 180 days 180 days ofdays of storage Visual No change No change No change No changeobservation Result No change No change No change No change of GCanalysis Result No polymer No polymer No polymer No polymer of GPCformed formed formed formed analysis Result Not detected Not detectedNot detected Not detected of RQ assay

Example 75

[0170] The same procedure as in Example 56 was followed except that a200-mL glass container coated with an opaque tetrafluoroethylene resinon 85% of the inside surface area thereof was used as a structure.

[0171] Upon GC, GPC and RQ assay, no deterioration in quality wasobserved, namely no impurity formation, no high-molecular substanceformation or no peroxide formation was detected.

Comparative Example 11

[0172] The same procedure as in Example 56 was followed except that a200-mL transparent glass container was used as a structure.

[0173] As a result of visual observation, GC, GPC and RQ assay, impurityformation, the formation of a high-molecular substance with a molecularweight (number average) of 1,500 and peroxide formation (12 ppm) werefound.

Reference Example 1

[0174] The same procedure as in Comparative Example 11 was followedexcept that 2-vinyloxyethyl propionate, which is the acryloyl group-freevinyl ether having similar structure as 2-vinyloxyethyl acrylate, wasused in lieu of 2-vinyloxyethyl acrylate.

Reference Example 2

[0175] The same procedure as in Comparative Example 11 was followedexcept that 2-ethoxyethyl acrylate, which is the vinyl ether group-freeacrylate ester having similar structure as 2-vinyloxyethyl acrylate, wasused in lieu of 2-vinyloxyethyl acrylate.

[0176] In Reference Examples 1 and 2, each composition in the containerafter 180 days of storage was evaluated by visual observation, GC, GPCand RQ assay. No deterioration in quality was observed, namely neitherimpurity formation nor high-molecular substance formation nor peroxideformation was detected.

[0177] According to the above results, it can be recognized that thevinyl ether group-containing (meth)acrylic esters have specificproperties, which are not seen in either acryloyl group-free vinylethers having similar structure or vinyl ether group-free acrylateesters having similar structure.

Example 76

[0178] A glass-made 3-liter five-necked flask equipped with a stirrer,thermometer, Oldershaw rectifying column, gas inlet tube and liquidaddition line was charged with 529 g of 2-hydroxyethyl vinyl ethercontaining 11 g of ethylene glycol divinyl ether, 1,502 g of ethylacrylate, 300 mg of phenothiazine and 10 g of dioctyltinoxide. Thecontents were mixed and stirred while introducing air into the liquidphase from the gas inlet tube, and heating was started on an oil bathmaintained at 130° C. This was the production starting point. Thereaction was continued while continuously adding that amount of theacrylate ester corresponding to the weight of ethyl acrylate found inthe ethyl acrylate-ethanol azeotrope, namely the distillate at the topof the Oldershaw rectifying column, to the reaction system through theliquid addition line. Samples were taken from the reaction system at30-minute intervals from the production starting point and the yield ofthe desired 2-vinyloxyethyl acrylate was followed by GC. The yieldbecame constant after 8 hours. The production time was thus 8 hours. Theyield of 2-vinyloxyethyl acrylate at that time was 95 mole percent.

Examples 77 to 95

[0179] The same procedure as in Example 76 was repeated except thatdifferent starting materials, different impurities contained therein,different polymerization inhibitors and different catalysts were used.The materials used, the amounts thereof, the reaction time, the productand the yield thereof as determined by GC for each run are shown inTable 9. In cases where methyl methacrylate was used as one of thestarting materials, that weight of methyl methacrylate corresponding tothe methyl methacrylate in the methyl methacrylate-methanol azeotropedistillate was continuously added to reaction system through the liquidaddition line. TABLE 9 Example 76 77 78 79 80 81 82 83 84 85 (Meth)acrylic ester AE AE AE MMA MMA MMA AE AE MMA MMA Amount charged (g) 15021502 1502 1502 1502 1502 1502 1502 1502 1502 OH-containing vinyl etherHEV HEV HEV HEV HEV HEV DEGV DEGV DEGV DEGV Amount charged (g) 529 529529 529 529 529 793 793 793 793 Impurity of formula (4) EGDV — EGDV EGDV— EGDV DEGDV DEGDV DEGDV — Content (g) 11 11 11 11 16 16 16 Impurity offormula (5) — MDOL MDOL — MDOL MDOL — MTOC — MTOC Content (g) 11 8 11 810 10 Impurity of formula (6) — — — — — — — — — — Content (g) Radicalpolymerization PTZ PTZ PTZ PTZ PTZ PTZ MEHQ MEHQ MEHQ MEHQ inhibitorAmount added (mg) 300 300 300 300 300 300 100 300 100 100 Radicalpolymerization — — — — — — TEMPOL TEMPOL PTZ inhibitor Amount added (mg)20 20 200 Catalyst DOTO DOTO DOTO DOTO DOTO DOTO DBTO DBTO DBTO DBTOAmount added (mg) 10 10 10 10 10 10 8 8 8 8 Reaction time (hr) 8 8 7.5 88 7.5 8 7.5 8 8 Product VEA VEA VEA VEM VEM VEM VEEA VEEA VEEM VEEMYield (mol %) 95 95 95 96 96 96 93 93 95 95 Example 86 87 88 89 90 91 9293 94 95 (Meth) acrylic ester MMA MMA MMA MMA AE AE AE MMA MMA MMAAmount charged (g) 1502 1502 1502 1502 1502 1502 1502 1502 1502 1502OH-containing vinyl ether DEGV DEGV DEGV DEGV BDV BDV BDV BDV BDV BDVAmount charged (g) 793 793 793 793 697 697 697 697 697 697 Impurity offormula (4) DEGDV DEGDV DEGDV DEGDV BDDV — — BDDV BDDV — Content (g) 1616 16 16 14 14 14 Impurity of formula (5) — — — — — MDOP — — MDOP —Content (g) 12 11 Impurity of formula (6) — — — — — — 4BVE — — 4BVEContent (g) 16 16 Radical polymerization MEHQ MEHQ MEHQ MEHQ MEHQ MEHQMEHQ MEHQ MEHQ MEHQ inhibitor Amount added (mg) 100 300 100 20 200 200200 200 200 200 Radical polymerization TEMPOL TEMPOL TEMPOL TEMPO TEMPOTEMPO TEMPO TEMPO TEMPO inhibitor Amount added (mg) 20 20 50 100 100 100100 100 100 Catalyst TBT DBTOAc BDBTLO ZrAA DBTO DBTO DBTO DBTO DBTODBTO Amount added (mg) 5 10 10 5 8 8 8 8 8 8 Reaction time (hr) 8.5 8 85.5 8 8 8 8 7.5 8 Product VEEM VEEM VEEM VEEM VBA VBA VBA VBM VBM VBMYield (mol %) 94 92 93 99 94 94 94 95 95 95

[0180] The symbols used in Table 9 are as follows.

[0181] As regards the (meth)acrylic ester, AE stands for ethyl acrylate,and MMA for methyl methacrylate. As regards the hydroxylgroup-containing vinyl ether, HEV stands for 2-hydroxyethyl vinyl ether,DEGV for diethylene glycolmonovinyl ether, and BDV for 1,4-butanediolmonovinyl ether. As regards the impurity of the general formula (4),namely the compound represented by the general formula (4) givenhereinabove, EGDV stands for ethylene glycol divinyl ether, DEGDV fordiethylene glycol divinyl ether, and BDDV for 1,4-butanediol divinylether. As regards the impurity of the general formula (5), namely thecompound represented by the general formula (5) given herein above, MDOLstands for 2-methyl-1,3-dioxolane, MTOC for 2-methyl-1,3,6-trioxocane,and MDOP for2-methyl-1,3-dioxepane. As regards the impurity of thegeneral formula (6), namely the compound represented by the generalformula (6) given herein above, 4BVE stands for 4-butenyl vinyl ether.As for the radical polymerization inhibitor, TEMPOL stands for4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl. As regards thecatalyst, DBTO stands for dibutyltin oxide, DOTO for dioctyltin oxide,TBT for tetrabutoxytitanium, DBTDAc for dibutyltindiacetate, BDBTLO forbis(dibutyltinlaurtae) oxide, and ZrAA for zirconia acetylacetonate. Theother symbols are the same as in Table 1.

Example 96

[0182] The same apparatus as used in Example 76 was charged with 529 gof 2-hydroxyethyl vinyl ether, 1,502 g of ethyl acrylate, 300 mg ofphenothiazine, 10 g of dioctyltin oxide and 11 g of ethylene glycoldivinyl ether, and the same procedure as in Example 76 was carried out.As a result of following by GC, the production time was found to be 8hours, after which the yield of 2-vinyloxyethyl acrylate was 95 molepercent.

Example 97

[0183] The same apparatus as used in Example 76 was charged with 529 gof 2-hydroxyethyl vinyl ether, 1,502 g of ethyl acrylate, 300 mg ofphenothiazine and 10 g of dioctyltin oxide, and the reaction wasstarted, with stirring, by immersing the apparatus in an oil bath at130° C. The same procedure as in Example 76 was followed except that 11g of ethylene glycol divinyl ether was added 2 hours after the start. Asa result of following by GC, the production time was found to be 9hours, after which the yield of 2-vinyloxyethyl acrylate was 95 molepercent.

Comparative Examples 12 to 17

[0184] The same procedure as in Examples 76, 79, 82, 84, 90 or 93 wasrepeated except that the hydroxyl group-containing vinyl ether used wasfree of any impurity. The starting materials, polymerization inhibitorand catalyst used, the amounts thereof, the production time found, theproduct and the yield thereof as determined by GC in each run are shownin Table 10. The symbols used in Table 10 are the same as in Table 9.TABLE 10 Comparative Example 12 13 14 15 16 17 (Meth) acrylic ester AEMMA AE MMA AE MMA Amount charged (g) 1502 1502 1502 1502 1502 1502OH-containing vinyl ether HEV HEV DEGV DEGV BDV BDV Amount charged (g)529 529 793 793 697 697 Impurity of formula (4) — — — — — — Content (g)Impurity of formula (5) — — — — — — Content (g) Impurity of formula (6)— — — — — — Content (g) Radical polymerization inhibitor PTZ PTZ MEHQMEHQ MEHQ MEHQ Amount added (mg) 300 300 100 100 200 200 Radicalpolymerization inhibitor — — TEMPOL TEMPOL TEMPO TEMPO Amount added (mg)20 20 100 100 Catalyst DOTO DOTO DBTO DBTO DBTO DBTO Amount added (mg)10 10 8 8 8 8 Reaction time (hr) 12 11 13 12 12 13 Product VEA VEM VEEAVEEM VBA VBM Yield (mol %) 95 96 93 95 94 95

Example 98

[0185] A glass-made 3-liter five-necked flask was charged with astirrer, thermometer, Oldershaw rectifying column, gas inlet tube andliquid addition line was charged with 529 g of 2-hydroxyethyl vinylether, 1,502 g of ethyl acrylate, 300 mg of phenothiazine and 10 g ofdibutyltin oxide.

[0186] On that occasion, the water content of the whole system asdetermined by the moisture meter was 0.1% by weight. While introducingair into the liquid phase from the gas inlet tube, the contents weremixed and stirred and then temperature raising was started by immersingthe flask in an oil bath at 130° C. While continuously adding thatamount of the acrylate ester corresponding to the weight of ethylacrylate in the ethyl acrylate-ethanol azeotrope distilling from the topof the Oldershaw rectifying column to the reaction system through theliquid addition line, the reaction was continued for 12 hours.

[0187] As a result of analysis by GC, the yield of the desired2-vinyloxyethyl acrylate was found to be 95 mole percent. When 10 g ofthe reaction system was added to 100 mL of hexane, the system wasdissolved to give a colorless transparent homogeneous solution.

Examples 99 to 108

[0188] The starting materials, polymerization inhibitor, basic compoundand catalyst used, the amounts thereof, the water content of the wholesystem as determine by using the moisture meter, the product and theyield thereof, and the result of the test for solubility in hexane areshown in Table 11 for each run. The symbols used in Table 11 are thesame as in Tables 1 to 10. In cases where methyl methacrylate was usedas one of the starting materials, that weight of methyl methacrylatecorresponding to the methyl methacrylate in the methylmethacrylate-methanol azeotrope distillate was continuously added toreaction system through the liquid addition line. TABLE 11 Example 98 99100 101 102 103 104 105 106 107 108 (Meth) acrylic AE MMA AE MMA MMA MMAMMA MMA MMA AE MMA ester Amount 1502 1502 1502 1502 1502 1502 1502 15021502 1502 1502 charged (g) OH-containing HEV HEV DEGV DEGV DEGV DEGVDEGV DEGV DEGV BDV BDV vinyl ether Amount 529 529 793 793 793 793 793793 793 697 697 charged (g) Radical PTZ PTZ MEHQ MEHQ MEHQ MEHQ MEHQMEHQ MEHQ MEHQ MEHQ polymerization inhibitor Amount added 300 300 300300 300 300 300 300 300 300 300 (mg) Basic com- — — — — NaOH — — — — — —pound Amount added 100 (mg) Catalyst DBTO DBTO DBTO DBTO DBTO TBT DBTDAcBDBTLO ZrAA DBTO DBTO Amount added 10 10 10 10 10 10 10 10 10 10 10 (mg)Water content 0.1 0.1 0.3 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 (wt %) ProductVEA VEM VEEA VEEM VEEM VEEM VEEM VEEM VEEM VBA VBM Yield (mol %) 95 9693 95 95 94 92 93 99 94 95 Solubility in Colorless, Colorless,Colorless, Colorless, Colorless, Colorless, Colorless, Colorless,Colorless, Colorless, Colorless hexane clear clear clear clear clearclear clear clear clear clear clear

Comparative Examples 18 to 23

[0189] The starting materials, polymerization inhibitor, basic compoundand catalyst used, the amounts thereof, the water content of the wholesystem as determine by using the moisture meter, the product and theyield thereof, and the result of the test for solubility in hexane areshown in Table 12 for each run. The symbols used in Table 12 are thesame as in Tables 1 to 10. TABLE 12 Comparative Example 18 19 20 21 2223 (Meth) acrylic ester AE MMA AE MMA AE MMA Amount charged (g) 15021502 1502 1502 1502 1502 OH-containing vinyl ether HEV HEV DEGV DEGVDEGV DEGV Amount charged (g) 529 529 793 793 793 793 Radicalpolymerization inhibitor PTZ PTZ MEHQ MEHQ MEHQ MEHQ Amount added (mg)300 300 300 300 300 300 Catalyst DBTO DBTO DBTO DBTO DBTO TBT Amountadded (mg) 10 10 10 10 10 10 Water content (wt %) 6.0 6.0 6.0 6.0 5.55.5 Product VEA VEM VEEA VEEM VEEM VEEM Yield (mol %) 93 94 89 91 92 90Solubility in hexane Slightly turbid Slightly turbid Slightly turbidSlightly turbid Slightly turbid Slightly turbid

Example 109

[0190] A glass-made 3-liter five-necked flask equipped with a stirrer,thermometer, Oldershaw rectifying column, gas inlet tube and liquidaddition line was charged with 529 g of 2-hydroxyethyl vinyl ether,1,502 g of ethyl acrylate, 300 mg of phenothiazine and 10 g ofdibutyltin oxide. The contents were mixed and stirred while introducingan 8% (by volume) oxygen gas (the balance being nitrogen) into theliquid phase from the gas inlet tube, and heating was started on an oilbath maintained at 130° C. The reaction was continued for 12 hours whilecontinuously adding that amount of the ethyl acrylate corresponding tothe weight of the ethyl acrylate found in the ethyl acrylate-ethanolazeotrope, namely the distillate at the top of the Oldershaw rectifyingcolumn, to the reaction system through the liquid addition line. Themolecular oxygen concentration in the gaseous phase during reaction was0.1 to 8% by volume. As a result of analysis by GC, the yield of thedesired2-vinyloxyethyl acrylate was found to be 96 mole percent. Nosolid matter formation was found either in the gaseous phase or in theliquid phase of the reaction system. As a result of analysis of theliquid phase by RQ assay, no peroxide was detected.

Example 110

[0191] The same procedure as in Example 109 was followed except that a8% (by volume) oxygen gas (the balance being nitrogen) was introducedinto the gaseous phase. The molecular oxygen concentration in thegaseous phase during reaction was 0.1 to 8% by volume.

[0192] As a result of analysis by GC, the yield of the desired2-vinyloxyethyl acrylate was found to be 96 mole percent. No solidmatter formation was found either in the gaseous phase or in the liquidphase of the reaction system. As a result of analysis of the liquidphase by RQ assay, no peroxide was detected.

Examples 111 to 116

[0193] The same procedure as in Example 109 was repeated except that the(meth)acrylic ester and/or hydroxyl group-containing vinyl ether and/orradical polymerization inhibitor used differed in species and/or theamounts thereof were varied and that the oxygen concentration was variedand further that a basic compound was used or not used. The speciesused, the amounts thereof, the vinyl ether group-containing(meth)acrylic ester produced and the yield thereof, the molecular oxygenconcentration in the gaseous phase during reaction, and the absence orpresence of a solid matter in the gaseous phase and in the liquid phaseof the reaction system and the result of analysis by RQ assay are shownfor each run in Table 13. The symbols used in Table 13 are the same asin Tables 1 to 12.

[0194] In cases where methyl methacrylate was used as one of thestarting materials, that weight of methyl methacrylate corresponding tothe methyl methacrylate in the methyl methacrylate-methanol azeotropedistillate was continuously added to reaction system through the liquidaddition line. TABLE 13 Example 111 112 113 114 115 116 (Meth) acrylicester AE MMA AE MMA AE MMA Amount charged (g) 1502 1502 1502 1502 15021502 OH-containing vinyl ether HEV HEV DEGV DEGV BDV BDV Amount charged(g) 529 529 793 793 697 697 Radical polymerization inhibitor PTZ MEHQPTZ MEHQ PTZ MEHQ Amount added (mg) 300 300 300 300 300 300 Basiccompound NaOH — NaOH — NaOH — Amount added (mg) 100 100 100 CatalystDBTO DBTO DBTO DBTO DBTO DBTO Amount added (mg) 10 10 10 10 10 10 Oxygenconcentration (vol %) 6 10 2 0.5 5 7 Molecular oxygen concentration ingaseous 0.05˜6 0.1˜10 0.03˜2 0.02˜0.5 0.08˜5 0.1˜7 phase during reaction(vol %) Product VEA VEM VEEA VEEM VBA VBM Yield (mol %) 96 97 93 95 9495 Solid matter formation in liquid phase No No No No No No Solid matterformation in gaseous phase No No No No No No Result of RQ assay Notdetected Not detected Not detected Not detected Not detected Notdetected

[0195] A glass-made 3-liter five-necked flask equipped with a stirrer,thermometer, Oldershaw rectifying column and liquid addition line wascharged with 793 g of diethylene glycol monovinyl ether, 1,502 g ofethyl acrylate, 300 mg of phenothiazine, 300 mg of AluminumN-nitrosophenylhydroxylamine and 10 g of dioctyltin oxide. While mixingand stirring, the flask was immersed in an oil bath maintained at 130°C., and the temperature was allowed to begin to rise. The reaction wascontinued for 12 hours while continuously adding that amount of ethylacrylate corresponding to the weight of the ethyl acrylate found in theethyl acrylate-ethanol azeotrope, namely the distillate at the top ofthe Oldershaw rectifying column, to the reaction system through theliquid addition line. As a result of analysis by GC, the yield of thedesired 2-(vinyloxyethoxy) ethyl acrylate was found to be 95 molepercent. No solid matter formation was found either in the gaseous phaseor in the liquid phase of the reaction system.

Example 118

[0196] The same procedure as in Example 117 was followed except that1,502 g of methyl methacrylate was used in lieu of ethyl acrylate.

[0197] As a result of analysis by GC, the yield of the desired2-(vinyloxyethoxy) ethyl methacrylate was found to be 97 mole percent.No solid matter formation was found either in the gaseous phase or inthe liquid phase of the reaction system.

Example 119

[0198] A glass-made 3-liter five-necked flask equipped with a stirrer,thermometer, Oldershaw rectifying column, gas inlet tube and liquidaddition line was charged with 793 g of diethylene glycol monovinylether, 1,502 g of ethyl acrylate, 300 mg of phenothiazine and 10 g ofdioctyltin oxide. The contents were mixed and stirred while introducingan 8% (by volume) nitrogen monoxide gas (the balance being nitrogen)into the liquid phase from the gas inlet tube, and heating was startedon an oil bath maintained at 130° C. The reaction was continued for 12hours while continuously adding that amount of ethyl acrylatecorresponding to the weight of the ethyl acrylate found in the ethylacrylate-ethanol azeotrope, namely the distillate at the top of theOldershaw rectifying column, to the reaction system through the liquidaddition line.

[0199] The molecular oxygen concentration in the gaseous phase duringreaction was 0.1 to 8% by volume.

[0200] As a result of analysis by GC, the yield of the desired2-(vinyloxyethoxy) ethyl acrylate was found to be 96 mole percent. Nosolid matter formation was found either in the gaseous phase or in theliquid phase of the reaction system.

Example 120

[0201] The same procedure as in Example 109 was followed except that an8% (by volume) nitrogen monoxide gas (the balance being nitrogen) wasintroduced into the gaseous phase. The molecular nitrogen monooxideconcentration in the gaseous phase during reaction was 0.1 to 8% byvolume.

[0202] As a result of analysis by GC, the yield of the desired2-(vinyloxyethoxy) ethyl acrylate was found to be 96 mole percent. Nosolid matter formation was found either in the gaseous phase or in theliquid phase of the reaction system.

Example 121

[0203] The same procedure as in Example 119 was followed except that1,502 g of methyl methacrylate was used in lieu of ethyl acrylate. Themolecular nitrogen monooxide concentration in the gaseous phase duringreaction was 0.1 to 8% by volume.

[0204] As a result of analysis by GC, the yield of the desired2-(vinyloxyethoxy) ethyl methacrylate was found to be 97 mole percent.No solid matter formation was found either in the gaseous phase or inthe liquid phase of the reaction system.

Comparative Example 24

[0205] The same procedure as in Example 109 was followed withoutintroducing the 8% (by volume) oxygen gas (the balance being nitrogen).After 2hours, a white solid was formed in the gaseous phase and liquidphase and, therefore, the reaction was discontinued.

Example 122

[0206] A lightproof structure, namely a 3-liter separable apparatus madeof SUS 316and equipped with a stirrer, thermometer holder, gas inlettube, liquid addition line and rectifying column was charged with 529 gof 2-hydroxyethyl vinyl ether, 1,502 g of ethyl acrylate, 300 mg ofphenothiazine and 10 g of dibutyltin oxide. The contents were mixed andstirred while introducing air into the liquid phase from the gas inlettube, and heating was started on an oil bath maintained at 130° C. Thereaction was continued for 12 hours while continuously adding thatamount of ethyl acrylate corresponding to the weight of the ethylacrylate found in the ethyl acrylate-ethanol azeotrope, namely thedistillate at the top of the Oldershaw rectifying column, to thereaction system through the liquid addition line.

[0207] The molecular oxygen concentration in the gaseous phase duringreaction was 0.1 to 21% by volume.

[0208] As a result of analysis by GC, the yield of the desired2-vinyloxyethyl acrylate was found to be 96 mole percent. No solidmatter formation was found either in the gaseous phase or in the liquidphase of the reaction system. As a result of analysis of the liquidphase by RQ assay, 3 ppm of peroxide was detected.

Example 123

[0209] The same procedure as in Example 122 was followed except that a15% (by volume) oxygen gas (the balance being nitrogen) was introducedin lieu of air. The molecular oxygen concentration in the gaseous phaseduring reaction was 0.1 to 15% by volume.

[0210] As a result of analysis by GC, the yield of the desired2-vinyloxyethyl acrylate was found to be 96 mole percent. No solidmatter formation was found either in the gaseous phase or in the liquidphase of the reaction system. As a result of analysis by RQ assay, noperoxide was detected.

Examples 124 to 131

[0211] The same procedure as in Example 123 was repeated except that the(meth)acrylic ester and/or hydroxyl group-containing vinyl ether and/orradical polymerization inhibitor used differed in species and/or theamounts thereof were varied and that the oxygen concentration was variedand further that a basic compound was used or not used. The speciesused, the amounts thereof, the vinyl ether group-containing(meth)acrylic ester produced and the yield thereof, the molecular oxygenconcentration in the gaseous phase during reaction, and the absence orpresence of a solid matter in the gaseous phase and in the liquid phaseof the reaction system and the result of analysis by RQ assay are shownfor each run in Table 14. The symbols used in Table 14 are the same asin Tables 1 to 13.

[0212] In cases where methyl methacrylate was used as one of thestarting materials, that weight of methyl methacrylate corresponding tothe methyl methacrylate in the methyl methacrylate-methanol azeotropedistillate was continuously added to reaction system through the liquidaddition line. TABLE 14 Example 124 125 126 127 128 129 130 131 (Meth)acrylic ester AE MMA AE AE MMA MMA AE MMA Amount charged (g) 1502 15021502 1502 1502 1502 1502 1502 OH-containing vinyl ether HEV HEV DEGVDEGV DEGV DEGV BDV BDV Amount charged (g) 529 529 793 793 793 793 697697 Radical polymerization inhibitor MEHQ PTZ TEMPO MEHQ PTZ MEHQ MEHQTEMPO Amount added (mg) 200 300 300 250 300 200 300 300 Basic compoundTEHA — — NaOH — TEHA NaOH — Amount added (mg) 100 100 100 80 CatalystDBTO DBTO DBTO DBTO DBTO DBTO DBTO DBTO Amount added (mg) 10 10 10 10 1010 10 10 Oxygen concentration (vol %) 7 10 8 5 0.5 0.2 1 2 Molecularoxygen concentration 0.1˜7 0.1˜10 0.1˜8 0.1˜5 0.1˜0.5 0.1˜0.2 0.1˜10.1˜2 in gaseous phase during reaction (vol %) Product VEA VEM VEEA VEEAVEEM VEEM VBA VBM Yield (mol %) 96 97 93 93 95 95 94 95 Solid matterformation in liquid No No No No No No No No phase Solid matter formationin No No No No No No No No gaseous phase Result of RQ assay Not detectedNot detected Not detected Not detected Not detected Not detected Notdetected Not detected

Example 132

[0213] The same procedure as in Example 123 was followed except that theupper lid-forming portion of the SUS 316-made separable apparatus usedin Example 123 was replaced with a transparent glass lid (in this case,the lightproof material SUS 316 accounted for 83% of the reactionapparatus structure inside surface area otherwise through which lightcould reach within the structure inside). The molecular oxygenconcentration in the gaseous phase during reaction was 0.1 to 15% byvolume.

[0214] As a result of analysis by GC, the yield of the desired2-vinyloxyethyl acrylate was found to be 96 mole percent. No solidmatter formation was found either in the gaseous phase or in the liquidphase of the reaction system. As a result of analysis by RQ assay, noperoxide was detected.

Comparative Example 25

[0215] The same procedure as in Example 109 was followed except that airwas introduced in lieu of the 8% (by weight) oxygen gas (the balancebeing nitrogen). The molecular oxygen concentration in the gaseous phaseduring reaction was 0.1 to 21% by volume.

[0216] As a result of analysis by GC, the yield of the desired2-vinyloxyethyl acrylate was found to be 96 mole percent. No solidmatter formation was found either in the gaseous phase or in the liquidphase of the reaction system. As a result of analysis by RQ assay,however, 17 ppm of peroxide was detected.

Comparative Example 26

[0217] The same procedure as in Example 109 was followed except that a15% (by volume) oxygen gas (the balance being nitrogen) was introducedin lieu of the 8% (by weight) oxygen gas (the balance being nitrogen).The molecular oxygen concentration in the gaseous phase during reactionwas 0.1 to 15% by volume.

[0218] As a result of analysis by GC, the yield of the desired2-vinyloxyethyl acrylate was found to be 96 mole percent. No solidmatter formation was found either in the gaseous phase or in the liquidphase of the reaction system. As a result of analysis by RQ assay,however, 12 ppm of peroxide was detected.

Example 133 Raw Material Recovery Procedure

[0219] The reaction mixture obtained by the same procedure as in Example127 was introduced into a glass-made 3-liter distillation apparatusequipped with a stirrer, thermometer holder, gas inlet tube, pressurereducing regulator and rectifying column. While introducing an 8% (byvolume) oxygen gas (the balance being nitrogen) into the liquid phase,the contents were mixed and stirred and heating was started on an oilbath maintained at 130° C. By reducing the pressure gradually from 667hPa to 67 hPa, ethyl acrylate and ethanol were allowed to distill out ofthe top of the rectifying column and the starting material ethylacrylate was recovered. The molecular oxygen concentration in thegaseous phase during raw material recovery procedure was 0.1 to 8% byvolume.

[0220] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 134 Raw Material Recovery Procedure

[0221] The same procedure as in Example 133 was followed except that a10% (by volume) oxygen gas (the balance being nitrogen) was introducedin lieu of the 8% (by volume) oxygen gas (the balance being nitrogen).The molecular oxygen concentration in the gaseous phase during rawmaterial recovery procedure was 0.1 to 10% by volume.

[0222] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 135 Raw Material Recovery Procedure

[0223] The same procedure as in Example 133 was followed except that a0.1% (by volume) oxygen gas (the balance being nitrogen) was introducedin lieu of the 8% (by volume) oxygen gas (the balance being nitrogen).The molecular oxygen concentration in the gaseous phase during rawmaterial recovery procedure was 0.02 to 0.1% by volume.

[0224] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 136 Raw Material Recovery Procedure

[0225] The same procedure as in Example 133 was followed except that thereaction mixture obtained by the same procedure as in Example 129 wasintroduced in lieu of the reaction mixture obtained by the sameprocedure as in Example 127. Methyl methacrylate and methanol were thusallowed to distill out of the top of the rectifying column and thestarting material methyl methacrylate was recovered. The molecularoxygen concentration in the gaseous phase during raw material recoveryprocedure was 0.1 to 8% by volume.

[0226] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 137 Raw Material Recovery Procedure

[0227] Following the procedure of Example 133, the contents in theapparatus were mixed and stirred while introducing an 8% (by volume)oxygen gas (the balance being nitrogen) into the liquid phase, and thetemperature was raised on an oil bath at 150° C. By reducing thepressure to 17 hPa, that portion of the starting material diethyleneglycol monovinyl ether remaining unreacted was caused to distill offfrom the top of the rectifying column and thus recovered. The molecularoxygen concentration in the gaseous phase during raw material recoveryprocedure was 0.1 to 8% by volume.

[0228] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 138 Raw Material Recovery Procedure

[0229] Following the procedure of Example 136, the same procedure as inExample 137 was followed. The molecular oxygen concentration in thegaseous phase during raw material recovery procedure was 0.1 to 8% byvolume.

[0230] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 139 Distillation/Purification Procedure

[0231] The mixture obtained by the same procedure as in Example 137 wasintroduced into a glass-made one-liter distillation apparatus equippedwith a stirrer, thermometer holder, gas inlet tube, pressure reducingregulator and rectifying column. While introducing an 8% (by volume)oxygen gas (the balance being nitrogen) into the liquid phase from thegas inlet tube, the contents were mixed and stirred and heating wasstarted on an oil bath maintained at 150° C. By reducing the pressuregradually to 13 hPa, 2-(vinyloxyethoxy)ethyl acrylate was caused todistill off from the top of the rectifying column for purifying thesame. The molecular oxygen concentration in the gaseous phase duringdistillation/purification was 0.1 to 8% by volume.

[0232] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis by RQ assay of the liquid phase and of thedistillate 2-(vinyloxyethoxy) ethyl acrylate, no peroxide was detected.

Example 140 Distillation/Purification Procedure

[0233] The same procedure as in Example 139 was followed except that themixture obtained by the same procedure as in Example 138 was introducedin lieu of the mixture obtained by the same procedure as in Example 137,to thereby causing 2-(vinyloxyethoxy)ethyl methacrylate to distill outfor purifying the same. The molecular oxygen concentration in thegaseous phase during distillation/purification was 0.1 to 8% by volume.

[0234] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis by RQ assay of the liquid phase and of thedistillate 2-(vinyloxyethoxy)ethyl methacrylate, no peroxide wasdetected.

Example 141 Water Washing Procedure

[0235] A 400-mL portion of the reaction mixture obtained by the sameprocedure as in Example 127 was introduced, together with 400 mL of a 1N aqueous solution of sodium hydroxide, into a glass-made one-literseparating apparatus equipped with a stirrer and a gas inlet tube. Whileintroducing an 8% (by volume) oxygen gas (the balance being nitrogen)into the gaseous phase from the gas inlet tube, the contents werestirred at room temperature for 1 hour, and then the contents wereallowed to stand for 1 hour, whereby they separated into an oil phase,an aqueous phase and a catalyst phase. After removing the aqueous phasecontaining unreacted diethylene glycol monovinyl ether, the catalystphase was removed by filtration.

[0236] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the separating apparatus. Furthermore,as a result of analysis of the oily phase by RQ assay, no peroxide wasdetected.

Example 142 Water Washing Procedure

[0237] The same procedure as in Example 141 was followed except that thereaction mixture obtained by the same procedure as in Example 129 wasintroduced in lieu of the reaction mixture obtained by the sameprocedure as in Example 127, to thereby remove the aqueous phasecontaining unreacted diethylene glycol monovinyl ether and the catalystlayer.

[0238] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the separating apparatus. Furthermore,as a result of analysis of the oil phase by RQ assay, no peroxide wasdetected.

Example 143 Raw Material Recovery Procedure

[0239] The reaction mixture obtained by the same procedure as in Example127 was introduced into a lightproof structure, namely a SUS 316-made3-liter distillation apparatus equipped with a stirrer, thermometerholder, gas inlet tube, pressure reduction regulator and rectifyingcolumn. While introducing a 15% (by volume) oxygen gas (the balancebeing nitrogen) into the liquid phase through the gas inlet tube, thecontents were mixed and stirred, and heating was started on an oil bathat 130° C. By reducing the pressure gradually from 667 hPa to 67 hPa,ethyl acrylate and ethanol were allowed to distill out of the top of therectifying column and thus the starting material ethyl acrylate wasrecovered. The molecular oxygen concentration in the gaseous phaseduring raw material recovery procedure was 0.1 to 15% by volume.

[0240] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 144 Raw Material Recovery Procedure

[0241] The same procedure as in Example 143 was followed except that an8% (by volume) oxygen gas (the balance being nitrogen) was introduced inlieu of the 15% (by volume) oxygen gas (the balance being nitrogen). Themolecular oxygen concentration in the gaseous phase during raw materialrecovery procedure was 0.1 to 8% by volume.

[0242] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 145 Raw Material Recovery Procedure

[0243] The same procedure as in Example 143 was followed except that a0.1% (by volume) oxygen gas (the balance being nitrogen) was introducedin lieu of the 15% (by volume) oxygen gas (the balance being nitrogen).The molecular oxygen concentration in the gaseous phase during rawmaterial recovery procedure was 0.02 to 0.1% by volume.

[0244] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 146 Raw Material Recovery Procedure

[0245] The same procedure as in Example 143 was followed except that thereaction mixture obtained by the same procedure as in Example 129 wasintroduced in lieu of the reaction mixture obtained by the sameprocedure as in Example 127, to thereby cause methyl methacrylate andmethanol to distill out of the top of the rectifying column forrecovering the starting material methyl methacrylate. The molecularoxygen concentration in the gaseous phase during raw material recoveryprocedure was 0.1 to 15% by volume.

[0246] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 147 Raw Material Recovery Procedure

[0247] Following the procedure of Example 143, the residue was stirredwhile introducing a 15% (by volume) oxygen gas (the balance beingnitrogen) into the liquid phase, and heating was started on an oil bathat 150° C. By reducing the pressure to 17 hPa, the unreacted portion ofthe starting material diethylene glycol monovinyl ether was distilledout of the top of the rectifying column for recovering the same. Themolecular oxygen concentration in the gaseous phase during raw materialrecovery procedure was 0.1 to 15% by volume.

[0248] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, no peroxide wasdetected.

Example 148 Raw Material Recovery Procedure

[0249] Following the procedure of Example 146, the same procedure as inExample 147 was followed. The molecular oxygen concentration in thegaseous phase during raw material recovery procedure was 0.1 to 15% byvolume.

[0250] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis by RQ assay of the liquid phase, no peroxide wasdetected.

Comparative Example 27 Raw Material Recovery Procedure

[0251] The same procedure as in Example 133 was followed except that a15% (by volume) oxygen gas (the balance being nitrogen) was introducedin lieu of the 8% (by volume) oxygen gas (the balance being nitrogen).The molecular oxygen concentration in the gaseous phase during rawmaterial recovery procedure was 0.1 to 15% by volume.

[0252] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis by RQ assay of the liquid phase, 12 ppm ofperoxide was detected.

Example 149 Distillation/Purification Procedure

[0253] The mixture obtained by the same procedure as in Example 147 wasintroduced into a lightproof structure, namely a SUS 316-made one-literdistillation apparatus equipped with a stirrer, thermometer holder, gasinlet tube, pressure reduction regulator and rectifying column. Whileintroducing a 15% (by volume) oxygen gas (the balance being nitrogen)into the liquid phase through the gas inlet tube, the contents weremixed and stirred, and heating was started on an oil bath at 150° C. Byreducing the pressure to 13 hPa, 2-(vinyloxyethoxy)ethyl acrylate wasallowed to distill out of the top of the rectifying column and the samewas thus purified. The molecular oxygen concentration in the gaseousphase during distillation/purification was 0.1 to 15% by volume.

[0254] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis by RQ assay of the liquid phase and of thedistillate 2-(vinyloxyethoxy) ethyl acrylate, no peroxide was detected.

Example 150 Distillation/Purification Procedure

[0255] The same procedure as in Example 149 was followed except that themixture obtained by the same procedure as in Example 148 was introducedin lieu of the mixture obtained by the same procedure as in Example 147,to thereby cause 2-(vinyloxyethoxy)ethyl methacrylate to distill out forpurifying the same. The molecular oxygen concentration in the gaseousphase during distillation/purification was 0.1 to 15% by volume.

[0256] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis by RQ assay of the liquid phase and of thedistillate 2-(vinyloxyethoxy)ethyl methacrylate, no peroxide wasdetected.

Comparative Example 28 Distillation/Purification Procedure

[0257] The same procedure as in Example 139 was followed except that a15% (by volume) oxygen gas (the balance being nitrogen) was introducedin lieu of the 8% (by volume) oxygen gas (the balance being nitrogen).The molecular oxygen concentration in the gaseous phase duringdistillation/purification was 0.1 to 15% by volume.

[0258] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the distillation apparatus. Furthermore,as a result of analysis of the liquid phase by RQ assay, 21 ppm ofperoxide was detected.

Example 151 Water Washing Procedure

[0259] A 400-mL portion of the reaction mixture obtained by the sameprocedure as in Example 127 was introduced, together with 400 mL of a 1N aqueous solution of sodium hydroxide, into a lightproof structure,namely a SUS 136-made one-liter separating apparatus equipped with astirrer and a gas inlet tube. While introducing a 15% (by volume) oxygengas (the balance being nitrogen) into the gaseous phase, the contentswere stirred at room temperature for 1 hour, and then the contents wereallowed to stand for 1 hour, whereby they separated into an oil phase,an aqueous phase and a catalyst phase. After removing the aqueous phasecontaining unreacted diethylene glycol monovinyl ether, the catalystphase was removed by filtration.

[0260] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the separating apparatus. Furthermore,as a result of analysis of the oily phase by RQ assay, no peroxide wasdetected.

Example 152 Water Washing Procedure

[0261] The same procedure as in Example 151 was followed except that thereaction mixture obtained by the same procedure as in Example 129 wasintroduced in lieu of the reaction mixture obtained by the sameprocedure as in Example 127, to thereby remove the aqueous phasecontaining unreacted diethylene glycol monovinyl ether and the catalystlayer.

[0262] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the separating apparatus. Furthermore,as a result of analysis of the oily phase by RQ assay, no peroxide wasdetected.

Comparative Example 29 Water Washing Procedure

[0263] The same procedure as in Example 141 was followed except that a15% (by volume) oxygen gas (the balance being nitrogen) was introducedin lieu of the 8% (by volume) oxygen gas (the balance being nitrogen).

[0264] No solid matter formation was observed either in the gaseousphase or in the liquid phase of the separating apparatus. However, as aresult of analysis of the oily phase by RQ assay, 10 ppm of peroxide wasdetected.

1. A vinyl ether group-containing (meth)acrylic ester composition whichcomprises a radical polymerization inhibitor and a vinyl ethergroup-containing (meth)acrylic ester represented by the followinggeneral formula (1): CH2=CR1-COO—R2-O—CH═CH—R3  (1) in the formula, R1represents a hydrogen atom or a methyl group, R2 represents an organicresidue and R3 represents a hydrogen atom or an organic residue.
 2. Avinyl ether group-containing (meth)acrylic ester composition as in claim1, which comprises a radical polymerization inhibitor, a basic compoundand a vinyl ether group-containing (meth)acrylic ester represented bythe following general formula (1): CH2=CR1-COO—R2-O—CH═CH—R3  (1) in theformula, R1 represents a hydrogen atom or a methyl group, R2 representsan organic residue and R3 represents a hydrogen atom or an organicresidue.
 3. A method of producing the vinyl ether group-containing(meth)acrylic ester composition according to claim 1, which comprisescausing a radical polymerization inhibitor, or both of a radicalpolymerization inhibitor and a basic compound to coexist with a vinylether group-containing (meth)acrylic ester represented by the followinggeneral formula (1): CH2=CR1-COO—R2-O—CH═CH—R3  (1) in the formula, R1represents a hydrogen atom or a methyl group, R2 represents an organicresidue and R3 represents a hydrogen atom or an organic residue.
 4. Amethod of handling a vinyl ether group-containing (meth)acrylic esterwhich comprises handling in the condition such that a waterconcentration in a liquid phase containing a vinyl ethergroup-containing (meth)acrylic ester is not more than 15% by weight andsaid vinyl ether group-containing (meth)acrylic ester being representedby the following general formula (1): CH2=CR1-COO—R2-O—CH═CH—R3  (1) inthe formula, R1 represents a hydrogen atom or a methyl group, R2represents an organic residue and R3 represents a hydrogen atom or anorganic residue.
 5. A method of handling a vinyl ether group-containing(meth)acrylic ester which comprises handling in the condition such thata molecular oxygen concentration in the gaseous phase in contact with avinyl ether group-containing (meth)acrylic ester is 0.01 to 15% byvolume and said vinyl ether group-containing (meth)acrylic ester beingrepresented by the following general formula (1):CH2=CR1-COO—R2-O—CH═CH—R3  (1) in the formula, R1 represents a hydrogenatom or a methyl group, R2 represents an organic residue and R3represents a hydrogen atom or an organic residue.
 6. A method ofhandling a vinyl ether group-containing (meth)acrylic ester whichcomprises handling a vinyl ether group-containing (meth)acrylic ester ina lightproof structure and said vinyl ether group-containing(meth)acrylic ester being represented by the following general formula(1): CH2=CR1-COO—R2-O—CH═CH—R3  (1) in the formula, R1 represents ahydrogen atom or a methyl group, R2 represents an organic residue and R3represents a hydrogen atom or an organic residue.
 7. A method ofhandling a vinyl ether group-containing (meth)acrylic ester whichcomprises handling a vinyl ether group-containing (meth)acrylic ester ina lightproof structure while keeping a molecular oxygen concentration inthe gaseous phase within said lightproof structure at 0.01 to 22% byvolume and said vinyl ether group-containing (meth)acrylic ester beingrepresented by the following general formula (1):CH2=CR1-COO—R2-O—CH═CH—R3  (1) in the formula, R1 represents a hydrogenatom or a methyl group, R2 represents an organic residue and R3represents a hydrogen atom or an organic residue.
 8. A method ofproducing a vinyl ether group-containing (meth)acrylic ester representedby the following general formula (1): CH2=CR1-COO—R2-O—CH═CH—R3  (1) inthe formula, R1 represents a hydrogen atom or a methyl group, R2represents an organic residue and R3 represents a hydrogen atom or anorganic residue, which comprises reacting a hydroxyl group-containingvinyl ether represented by the following general formula (2):R3-CH═CH—O—R2-OH  (2) in the formula, R2 represents an organic residueand R3 represents a hydrogen atom or an organic residue, with a(meth)acrylic ester represented by the following general formula (3):CH2=CR1-COOR4  (3) in the formula, R1 represents a hydrogen atom or amethyl group and R4 represents an organic residue, and said hydroxylgroup-containing vinyl ether containing at least one compound selectedfrom the group consisting of a divinyl ether represented by thefollowing general formula (4): R3-CH═CH—O—R2-O—CH═CH—R3  (4) in theformula, R2 represents an organic residue and the two R3 groups are thesame or different and each represents a hydrogen atom or an organicresidue, a 2-substituted-1,3-dioxo compound represented by the followinggeneral formula (5): in the formula, R2 represents an organic residueand R3 represents a hydrogen atom or an organic residue, and anunsaturated bond-containing vinyl ether represented by the followinggeneral formula (6): R3-CH═CH—O—R5  (6) in the formula, R3 represents ahydrogen atom or an organic residue; R5 represents an organic residuecontaining an unsaturated bond represented by —CR6=CR7-; and R6 and R7are the same or different and each represents a hydrogen atom or anorganic residue.
 9. A method of producing a vinyl ether group-containing(meth)acrylic ester represented by the following general formula (1):CH2=CR1-COO—R2-O—CH═CH—R3  (1) in the formula, R1 represents a hydrogenatom or a methyl group, R2 represents an organic residue and R3represents a hydrogen atom or an organic residue, which comprisesreacting a hydroxyl group-containing vinyl ether represented by thefollowing general formula (2): R3-CH═CH—O—R2-OH  (2) in the formula, R2represents an organic residue and R3 represents a hydrogen atom or anorganic residue, with a (meth)acrylic ester represented by the followinggeneral formula (3): CH2=CR1-COOR4  (3) in the formula, R1 represents ahydrogen atom or a methyl group and R4 represents an organic residue, inthe presence of not more than 5% by weight of water.
 10. A method ofproducing a vinyl ether group-containing (meth)acrylic ester representedby the following general formula (1): CH2=CR1-COO—R2-O—CH═CH—R3  (1) inthe formula, R1 represents a hydrogen atom or a methyl group, R2represents an organic residue and R3 represents a hydrogen atom or anorganic residue, which comprises reacting a hydroxyl group-containingvinyl ether represented by the following general formula (2):R3-CH═CH—O—R2-OH  (2) in the formula, R2 represents an organic residueand R3 represents a hydrogen atom or an organic residue, with a(meth)acrylic ester represented by the following general formula (3):CH2=CR1-COOR4  (3) in the formula, R1 represents a hydrogen atom or amethyl group and R4 represents an organic residue, in an atmosphere suchthat a molecular oxygen concentration is 0.01 to 10% by volume.
 11. Amethod of producing a vinyl ether group-containing (meth)acrylic esterrepresented by the following general formula (1):CH2=CR1-COO—R2-O—CH═CH—R3  (1) in the formula, R1 represents a hydrogenatom or a methyl group, R2 represents an organic residue and R3represents a hydrogen atom or an organic residue, which comprisescarrying out said method of producing a vinyl ether group-containing(meth)acrylic ester in a lightproof structure.
 12. A method of producinga vinyl ether group-containing (meth)acrylic ester as in claim 11represented by the following general formula (1):CH2=CR1-COO—R2-O—CH═CH—R3  (1) in the formula, R1 represents a hydrogenatom or a methyl group, R2 represents an organic residue and R3represents a hydrogen atom or an organic residue, which comprisescarrying out said method of producing a vinyl ether group-containing(meth)acrylic ester in a lightproof structure in an atmosphere such thata molecular oxygen concentration in the gaseous phase within saidlightproof structure is 0.01 to 15% by volume.
 13. A method of purifyinga vinyl ether group-containing (meth)acrylic ester represented by thefollowing general formula (1): CH2=CR1-COO—R2-O—CH═CH—R3  (1) in theformula, R1 represents a hydrogen atom or a methyl group, R2 representsan organic residue and R3 represents a hydrogen atom or an organicresidue, which comprises carrying out said method of purifying a vinylether group-containing (meth)acrylic ester in an atmosphere such that amolecular oxygen concentration in the gaseous phase in the purificationsystem is 0.01 to 10% by volume.
 14. A method of purifying a vinyl ethergroup-containing (meth)acrylic ester represented by the followinggeneral formula (1): CH2=CR1-COO—R2-O—CH═CH—R3  (1) in the formula, R1represents a hydrogen atom or a methyl group, R2 represents an organicresidue and R3 represents a hydrogen atom or an organic residue, whichcomprises carrying out said method of purifying a vinyl ethergroup-containing (meth)acrylic ester in a lightproof structure in anatmosphere such that a molecular oxygen concentration in the gaseousphase in the purification system is 0.01 to 15% by volume.
 15. Themethod of purifying a vinyl ether group-containing (meth)acrylic esteraccording to claim 13, wherein said purification of a vinyl ethergroup-containing (meth)acrylic esters is carried out in the manner ofdistillation purification.
 16. A method of producing the vinyl ethergroup-containing (meth)acrylic ester composition according to claim 2,which comprises causing a radical polymerization inhibitor, or both of aradical polymerization inhibitor and a basic compound to coexist with avinyl ether group-containing (meth)acrylic ester represented by thefollowing general formula (1): CH2=CR1-COO—R2-O—CH═CH—R3  (1) in theformula, R1 represents a hydrogen atom or a methyl group, R2 representsan organic residue and R3 represents a hydrogen atom or an organicresidue.
 17. The method of purifying a vinyl ether group-containing(meth)acrylic ester according to claim 14, wherein said purification ofa vinyl ether group-containing (meth)acrylic esters is carried out inthe manner of distillation purification.